1. Close adherence to stats - in general - seems like a good idea. In earlier versions enemies had higher HP, but lower armor. I don't know if any of that was reversed, but it probably should be because it affects the balance between things which use attack rolls and things which use saving throws. HOWEVER, I don't think it would be a good idea to put in Intellect Devourers unchanged with no way for the low-level players to avoid being rendered catatonic by "Devour Intellect", so that's a warning flag to me that you may be prioritizing purism a little too much.
2. Not everyone is going to agree on what the best way to translate the 5e rules for this adaptation. For example, I don't agree at all with your assertion that potions shouldn't be a bonus action. This is because you take a lot more damage than what potions are good for. If you're hurt by an enemy, take a full action to use a potion, then get hurt by the same attack again, you're going to end up worse off than ever. That makes using a full action to take a potion useless most of the time.
3. Larian isn't likely to budge on this, but I would like a party size of at least 5 for more flexibility.
