I don't see why not. I play on very hard and while I don't usually pickpocket I'm usually a tank by lvl 15 or so. Shouldn't be too tough, go for it.
yeah, seems possible.
Id toss my skills in either melee or anything I can get silenced, the lockpick skills asap, maybe pick pocket skills if that interests you, the explosive skills so I can set mines as trap, and any sneak/crit skills under luck or agi would help. Thinking this would end up being more of a luck/agi build with perception being important too, but not as.
With Sneak and Ninja you don't even need straight damage or upgrade perks. I have them anyway purely because I'm a cruel [censored]