I'll preface this by saying that Larian has to juggle three ideas - an adaptation of 5E mechanics, a continuation of Baldur's Gate 1&2, and the flavor of their own team akin to Divinity Original Sin 1&2. Inherently, they've chosen their own flavor of verticality and aesthetics, with much of 5Es mechanics, and a loose (if not largely absent) story of BG.
However, I'm not opposed to some sort of optional tuning pack (similar to how Xcom 1&2 offer variant rules at the start of the game) to change certain factors away from the base experience.
Anyhow, as for your suggestions;
1) I'm totally cool with warbows/oversized longbows, or basically any of the ranged options (I imagine Heavy Crossbows would require some strength to wind up in a short period of time) using Strength in some way.
2) I suspect this is the broad appeal of the Battlemaster Fighter, in which I think the Martial Adept feat is basically this.
3) This is how I've rolled it on the tabletop, so yep.
For many of the class decisions, Larian has said they were aiming for 10th level as the cap, but considered changing it to 12th level to fit more progression in, so many of the higher level balancing is unlikely to make it in game. As a discussion for the tabletop;
Barbarian: As far as increased critical range goes, I think that was the territory of the Champion Fighter subclass, and thus making it partially viable to multiclass between them (though, not really tbh, given redundant Extra Attack and proficiencies).
Berserker: Missing out on one weapon attack seems like a low priority to me (though doing damage earlier is technically better than doing it later, sure). If your average Ranger/Warlock has to burn a bonus action to cast or apply Hunter's Mark.Hex, then I think the bonus action defecit is okay.
Fighter: I do think Fighter get the short end of the stick as far as martials go. That said, getting back every use of Action Surge, Indomitable and Second Wind with each initiative roll is ... a bit much. Whether a classes capstone should be "you get back resources when you roll initiative" or the more unique ones like Cleric, Wizard, Barbarian, or ... *shudder* Druid, is probably a better consideration to have.
Arcane Archer: A decent buff, but one that probably incentivises small multiclass dips rather than a pure class. I'd probably have it scale off Intelligence, which is slightly palatable given Fighters get more ASIs (though it does compete with Sharpshooter/Crossbow Expert and Dexterity).
Monks: This is a bit tricky, because constant Ki means constant Stunning Strike. The most I could grant is you can do a small meditation outside of combat (recenter your Chi, that sort of thing) similar to how they made Prayer of Healing an instant out of combat thing. You'd have a pool of this meditation Ki equal to your Wisdom. So you can easily start each fight with more Ki, you can burn through your per level reserve (which you'd probably have to halve to compensate) and still have room for the Way of the Four Elements to burn through Ki, value their Short rest, etc.
As for free Flurry of Blows at 20th level, I'd probably just double the damage die of unarmed attacks and leave it at that. Even allowing for 4 Ki when your per level Ki is below 4 is still decent.
Rangers: They're probably in a strong spot in this game, having great weapons, good armor, decent spells, good skills, and have what is essentially a subclass at 1st level before getting their actual subclass. I don't like it (even less so making them Fighters), but I can respect the viability at least.
Rogue: Crippling Strike feels like an entire subclass feature. Better yet, replace the Assassins lackluster Imposter and Infiltration features with this (though maybe replace one of them with at will Disguise Self).
Assassin: Depending on how its implemented, Assassin would be very powerful in this game, mostly because of how stealth works in this game. Going on a shove spree in this game is fairly easy, and I can only imagine a critical hit spree (plus if critical hits do one die of max damage) would be quite effective. Larian seems to have padded enemy HP to make one shot kills less likely, but given how accessible rests are, its mostly a setup to make us burn resources.
Sorcerers/Warlocks: I suspect this is an unpopular opinion, but I actually don't think either should get extra spells than what the PHB outline. I actually like the idea that Sorcerers have limited natural spells similar to Bards, and that inherently some classes should have less spell flexibility than others. Wizards should clearly not be able to copy any spell list via scroll, which should probably be a feature of the Bard (limited to Magical Secrets, if we ever get it).
Overall though, I'm okay with of these as tuning changes, just as long as they're all individual choices.