Aye, pretty much all passive DC stuff like that -- both for traps and locks, and probably some other junk -- increase with depth. I think the rationalization is that the earlier levels kill off the less competent lockmakers.
As for rogues -- sneaky, skill focus (Use Magic), stealth around picking up wands and the blowing everything into little pieces. Wands get completely and utterly ridiculous incredibly quickly, and there's literally nothing else in the game as capable of exploiting the involved skillchecks better than rogues, iirc. You can stab a few things in the process, I guess, or start as drow (or elf, I guess? I think they start with something both usable and ranged, too) and crossbow things until you can wand stuff to death or whatev'. Almost definitely want high int -- if you can live long enough to enable skill mastery with a high int rogue you can pretty promptly start doing silly things like permastealthing across the ceiling blowing everything up with doomwands. Skills are pretty great. Stealth is pretty alright.
There's plenty of other ways to run 'em, too. I've seen other folks do good things with some assassin and/or shadow-whatever prestige classing.
With monks, mostly just use your quarterstaff or whatever for the first bit. Don't forget you've got the chakram -- might as well use it. Once you've got some BAB in you, a few feats stuck in your fists, and some skills and class features enabled you do pretty decently as plain ol' melee. You can stealth around as well, if you want. Probably go lizard for the native armor, I'unno, or orc for the late game (disease immunity, omnomnom). Eventually you'll be immune to a lot of junk (orc luv, baby) and have some pretty killer skill rolls (especially for stuff like jump, which is actually pretty awesome if you've got enough bonus in it to make the friggin' jumps) as well as fists that can actually hurt critters and pretty quick feet. Maybe take a level of druid at some point to pick up magic fang (and hell, lifesight and longstrider while you're at it) if you're feeling frisky. I think there's a couple of monk gods that are okay with druids, if my memory's not failing.