if your wizard can only cast level 3 spells then no you can't learn a level 4 scroll however yes you could just cast it from the scroll
as for grubs, vamp-boy is happy to shub those suckers in to give him more power and i could also see gall poping them if you want to try using them that way instead of your character
i don't see why the evil path is blocked by rp but its your run
