Leprosy is not recommended. Not only is limb-loss completely random, it'll also hit your stats. Angering Sophos is an interesting approach, and very do-able, points to Zulox for originality. It's really hard to find spell-casters that'll target limbs, and letting them take your limbs is dangerous, they'll probably kill you.
It depends. If you have equal skill with both weapon types, then yes, flaming swords are the better choice. The burn damage can't be blocked, which is great against heavily armoured foes. For whips though, no, not unless it's a whip of thievery.