i can answer few of the questions. correct me if im wrong here.

spell for dumb races are alright, i dont know what it takes for a sleep spell to succed, expect % and victem vs spell.

Vault are only good if you have them slept, though if you fail you can hurt yourself badly, there are en edge to avoid this. Cleave to alot of damage, but lags yourself so the enemie can flee, very good in closed room, or if you have a alley to bash.
Yes, vault let you have the next command.

Faceslash can lag to, but its more like a trip lag. remember there are wands you can open fights with. (that lags to)

Lashes works best for high dex races.

when you get your first unholy control, i think its after 15 souls.