Things are fairly subject to change i think but some less so because it could have balance issues. but with mods all of this seems possible.
Initiative seems to be because its faster (especially in huge battles) and better for multi player, there might be an option but i dont see it happening as something beyond one of their "mod pack" things from DOS2 due to its effect on balance
Ability scores i see as a mod thing most likely. Mods or editors should be able to fix this by rolling in game or just at your table and editing in a file. i would love to see ability to roll but i also understand using a buy in because in BG you would just randomize to get bigger and bigger pool and allocate how you like and you could gimp yourself heavily if it was just normal rolls and you rolled terrible.
I would love 5 but the UI seems to be built around 4 with a follower. Lets hope this changes or mods can change this
Rules i guess we will get to see when it goes EA but a tutorial which they said wasnt in the game could do a lot to teach you and see how close it is but i would like just a list of changes and such
For me i would love to see an option to display attack rolls as a dice over the head, not a change to how it works but just a visual would be nice
Different rule set for DM mode if we get it so things like potions are not BA but more true to Tabletop but also maybe room to add in house rules
