Nice to see the game back!
First regarding the question: I like more the current version with rolls. As I understand, it means that even a mistaken choice can result in success, while a right choice is not necessarily guaranteed a fortunate outcome. In my opinion, it makes the game more thrilling.
As for the choices...
1) Ignoring a wet and slimy snake-like creature (exciting!) is certainly risky, especially since it creeped into clothes so swiftly. So I think it's much better to remove it by...
iii) first to discard this: it makes a clever use of frost magic, but I really doubt that it's a good idea to actively inspire the slithering being to move down.
i) this is likely to solve the problem fully, but Ivy either gets soggy disadvantages or naked (really nice, but the clothing still gives 1 damage reduction which might be useful).
ii) this looks like a temporary solution, since Ivy blocks the movement of the "snake", but it might just wait on her upper body or still do something nasty (or just bite).
So basically I am thinking between b)ii and b)i, more or less going with b)ii: first prevent "snake" from sliding down by wrapping one arm around stomach, then try to force it away with second hand (if it's possible to so do, certainly).
But if other readers think that it's better to play safe (even at the expense of soggy disadvantages/getting naked), then I don't mind b)i either.
What to do with snake if it's forced out... I dunno, I kinda don't want to kill it needlessly, and capturing it also seems troublesome (we'll need to carry it around, and that seems inconvenient). So perhaps just discard, but also try to see if it's a real snake - or just a watery tentacle.
2) Here it's trickier, so many options. Generally, I think we'd better avoid going into deep water due to aquatic creatures. Getting into a tunnel from where a "snake" fell is also quite risky, and it's likely that we might encounter more snakes in other narrow paths (where it's much harder to get rid of them).
But it's also better to reach the originally blocked tunnel... ugh, all three paths there are unpleasant - it's blockage, possible snakes, deep water.
I kinda lean towards checking the next tunnel (since returning to the original tunnel is risky), even if we might get needlessly further into maze. If we do so (2b), it's probably the safest to do so up the slope (b)i).
Also, an idea about maps: it might be useful to mark different paths with corresponding options (if there is a choice about where to go).
Basically something like this. Though I likely have gotten some paths wrong due to a bit of trouble with spatial imagination.