I agree with some of those, but not all.
More than two possible answers in dialogue can quickly spiral out of control. Going from two to four answers quadruples the writing workload, so keep that in mind.
If you add in a bunch more skills, then sure, some skills which require both Ability X AND Ability Y would work, but right now the amount of skills per class is small enough that adding AND requirements would force you into certain builds whether you want to or not. I've made the suggestion of OR requirements, so Phoenix Dive would require EITHER WotW 3 OR Fire Elementalist 3. I don't think either of those are happening in the base game, though.
Played The Witcher a lot, have you? A healing potion which lowers your max HP does not seem like a useful idea at all. Especially not with the existence of other healing methods, some of which which provide BOOSTS to stats and not debuffs. Some different drawback would be better.
I wouldn't mind getting an empty flask after drinking a potion, though.
