didn't see any

Yes, you do encounter more swarms from time to time, but you should usually have AoE spells or weapons that do elemental damage.

later swarms have far more HP so torches are literally useless against those. so not only you should have AoE and elemental damage - you must have those, or else.

rope is useful a few times not Required but I beleive it gets you a little extra xp a couple of times

there are quite a few ropes to find so there is no need to conserve those. i think the question was "if I keep something instead of using it will I feel smart later" - the answer is no, a far as I;m concerned. As a side note: all the DC lowering actions like ropes and stuff do is robbing you of exp. So, I'd say never use anything and always go for highest DC. It is stupid that the game punishes you for being smart and preparing, but this is how it works.