The skills in pickpocket and pick lock do not increase with level (they're skills in 3d ed you've gotta put skill points in them, which you get every level, no matter which class you are, as long as you have at least 1 lvl rogue you can optimise these skills), I dont know anything about disarming and setting traps (why would she set traps if she frees animals anyway?
). Backstab (sneak attack in 3d) does however increase with level and if you wanna be good at it you've gotta take several levels of rogue.