question about spells and thieve ops

I just might not understand. Does the success of spells depend on WPA or the amount of wizzies you actually have.

Same question applies to Thieves...I am just wondering what i need to do to get a better success rate. Also does it matter on the amount of thieves that you send when you are sending to have success...For example. I have 5 TPA and send only 500 or 5000 thieves, will I succeed based on TPA or would I want to send more like 2500 to have success more often? Also does this depend on the spell or thieve ops and if so can someone provide a list so I can have a better understanding? Thank you.

http://wiki.utopia-game.com/index.php?title=Mystics