A Simpler Start for My Online LotFP Game

So I've thought about my tentative house rules for the online campaign that I hope to start soon, and I think I might be forcing my players to jump off of the deep end if I subject them to all of that right away. Most of them are probably unfamiliar with both the specific set of rules and the old-school/OSR style, so adding a whole bunch of weird, experimental rule changes on top of that might overcomplicate things or give a false impression of what the typical experience of the game is like (assuming there is such a thing). If I were new to the game, I could easily see myself playing for the first time in a campaign with all kinds of oddball rule changes and then playing what I thought was the same game elsewhere and practically having to learn everything over again. "What? Different character classes get different saving throws? And what's up with all these different categories?" Maybe that wouldn't be as hard as it sounds in my head, but I bet that it would be more beneficial to start off simply and then introduce the more unorthodox ideas later, maybe even in a different campaign. There will hopefully be time for playtesting after everyone has gotten comfortable.

I do want to use some house rules right from the beginning, but not so many of them or ones that are quite so different from what the players could read in the free rulebook. So for now, here are the few house rules I definitely want to start with. To quote the post I linked to above, "I should also note that most of these are lifted from the LotFP Playtest Document, either as-is or in modified form. I may not explicitly mention this in all cases, so please keep in mind that credit for a lot of this material should go to James Raggi."

UPDATED ON APRIL 25, 2017 - See sections marked "EDIT" and the "Summoning with the Arcana Skill" section.

Ability Score Checks - When a PC attempts to accomplish certain risky actions that are not covered by a Skill, the DM may ask for an Ability Score Check (Strength Check, Charisma Check, etc.) in order to determine success or failure. The player rolls 3d6. If the result is equal to or less than their character's relevant ability score, they succeed. If the result is higher, they fail.
EDIT: I am considering two alternatives to the above rule.

1. As above, except that if the DM decides that a check should be somewhat more difficult than usual, the DM can require the player to roll a d20 instead of 3d6. If the DM decides that a check should be much more difficult, the DM can require the player to roll a d30 instead of 3d6.
2. As above, except that the player rolls a d20 for all skill checks.

EDIT ON 5/16/17: I'm 90% sure I'm just going to go with Option 2.

Character Classes - There are two four options regarding the available character classes that I am considering. Before the campaign beings, I would like my players to make a group decision about which one to use. I would be glad to answer questions about these choices, of course.
EDIT: I added two more options.

1. Available character classes are the Fighter, Specialist, Magic-User, Cleric, Elf, Dwarf, and Halfling. Class abilities operate by the book, or RAW (Rules as Written) at the beginning of the campaign, but we can negotiate tweaks to these rules over time if desired. Also, new classes can be "unlocked" or discovered through play, and thus added to the roster of character creation options in the future. Members of the Elf, Dwarf, and Halfling classes should note that their characters may face severe discrimination and hostility in human communities, and that NPC members of these classes will probably be extremely rare. I may or may not implement my house rules from this post regarding the Elf.
2. Available character classes are the Fighter, Magic-User, Cleric, and Alice (or Fool). In addition to their usual class abilities, all characters gain skill points as per the Specialist, which is no longer a separate class. No class starts with free specialist tools. The Alice class will probably use the HP, Saving Throw, and XP chart of the Specialist, and the Level Up table for the Alice will be altered to remove the entries that improve the character's Saving Throws or increase skill points. I reserve the right to alter the table in other ways before the campaign begins. Also, new classes can be "unlocked" or discovered through play, and thus added to the roster of character creation options in the future. However, I will alter these new classes to fit the house rules above if I feel it is helpful or necessary.
3. The Classic Trio
4. Separate Race and Class

P.S. I still want to try out my crazy "everybody's a Fighter" thing I mentioned previously, but since I don't think it's very old-school compared to the options above (among other reasons), I have decided not to do so with this group just yet.

Critical Hits - If a natural 20 is rolled to hit, the attack automatically hits and does maximum damage (e.g. 8 if the attack would normally do 1d8 damage).

Experience Points - No more than one level of experience can be gained per session. If a character gains enough experience points to gain more than one level in a single session, the character only gains one level for the time being. In order to reach the next level, the character must gain at least 1 additional experience point in a future session. This continues until the character does not have enough experience points for the next level. "Excess" experience points are not lost.

Increasing HP - Upon leveling up, roll a number of Hit Dice equal to your new level (up to level 9, after which each additional level gives you less, as per Rules & Magic). If you roll an amount higher than your previous maximum, that becomes your new maximum HP. If you roll an amount equal to or lower than your previous maximum, your new maximum is your previous maximum plus 1.

Read Magic - This spell is no longer necessary.

Replacement Characters - When your character dies, you have two options.

1. Create a new character. This character starts with an amount of XP (and appropriate level) determined by the house rule outlined in this post.
2. Use one of your last character's NPC retainers as your new character.

The Rule of One (Paraphrased from the Playtest Document) - If the DM just really wants an excuse to screw with the players, they can roll a d6. On a 1, the DM has permission to add a problem or complication to the current situation.

The Rule of Reasonableness (Paraphrased from the Playtest Document) - If the chance of failure wouldn't be interesting, or if it seems reasonable that something should just work, let the PCs automatically succeed at what they're doing.

Skill List - Available skills include the following:

• Arcana (This works mostly like the "Mystical Traditions" skill from Santa is Dead, plus this can be used to activate certain magic items, like scrolls and wands, that can normally only be used by Magic-Users or Elves.)
• Architecture (I might change this to Engineering, as per Papers & Pencils)
• Bushcraft
• Climb (I might change this to Athletics, as per Papers & Pencils.)
• Languages
• Medicine (I might call this First Aid)
• Seamanship
• Sleight of Hand
• Sneak Attack
• Stealth
• Swimming (EDIT: Added after the release of Veins of the Earth. If I change Climb to Athletics, I may remove this skill again and use Athletics for swimming purposes.)
• Tinker
• Others that may be added over time

The skills "Open Doors" and "Search" have been removed, as per my notes HERE.
EDIT: Added Arcana and Swimming, and removed Luck.
EDIT ON 5/16/17: I think that I will mostly follow these guidelines from Ten Foot Polemic when it comes to determining how skill rolls actually work.

Strength - No longer affects Open Doors because this skill has been removed. (If an Open Doors check would ordinarily be called for, an ability score check can be used instead.)

Summoning with the Arcana Skill - When summoning a creature with the Arcana skill, rather than the Summon spell, ignore Steps One and Two (Rules & Magic, p. 134). Instead, simply roll 1d10 to determine the creature's Hit Dice. The Arcana skill cannot be used to summon a creature of more than 10 Hit Dice.
Summoning a creature with the Arcana skill will always result in the summoned entity being hostile to the summoner unless at least one Thaumaturgic Circle or at least one Sacrifice is used. If no Thaumaturgic Circle or Sacrifice is used, treat a successful Domination roll as a basic failure (i.e. the creature lashes out). A character who is not a Magic-User (or Elf) can create Thaumaturgic Circles just like a Magic-User as long as they have at least 2 points in the Arcana skill. Any character can perform a Sacrifice.
Summoning a creature with the Arcana skill takes an hour, so it is a slower process than simply casting the Summon spell. (Added on April 25, 2017)