Picking of Pockets...

I'm about to start up a thief who is going to love picking those pockets but its a skill I've rarely used. Besides a ring from Ribald I'm not sure I've ever really used it.

I'm not a big fan of reloads so what kind of score would I need to be relatively consistent with my thefts?

I know I can drink a potion but I don't know where they are or how many are in BG.

I'm going to have another thief for traps and mages for my stealth and locks so I'm fine with overloading on the pickpocket skill.

Also, is there any chance to check the percentage of success before hand?

Thanks!