I have no problem whatsoever with stuff like the dipping and environmental actions. It might not be in the core rules, but from what I have read 5e is more rules light. Having an interaction for lighting flammable materials on fire is a good thing to put in a game like this and IMO a sensible building upon of the rules. Stuff like that has happened more than once in games I have DM'd and games I have played in-I feel it would be pretty ruleslawyer-y thing for a DM to stamp their foot down and say 'no you can't light the pool of lantern oil on fire' for example. I just don't want more Blackpits fights down the road.
It *could* use some tweaking- I think the food healing is a bit much and makes the expensive healing potions redundant. They'd be neat to have as sort of a resource for traveling if Larian was going for a more BG I exploration style, or as a requisite for rest healing to reign in the long-rest spam. Acid giving -2 ac feels really unintuitive, and dare I say it, unimerssive. Also really easy to mix up with poison, which is the surface you really need to watch out for, not acid.