Questions on thieving skills

[Bawookles]

Hey, all!
Looking forward to IWD2 but I've got some thieving questions concerning skills such as "search", "disable device", etc.
In 2e rules, you knew when your thief was maxed out at "find traps" or "pick locks" (you reach 100%) but how does it work with the thieving skills in 3e? Okay, you add on skills like +2 to "search" and stuff but how do you know when you've effectively put enough skills in that category?
Secondly, is it neccessary to ever put more than one level into the rogue class? I mean once you've put just one level into rogue you can than get all the thieving skills without cross-classing and you can build up your character in other levels of bard or fighter or whatever.
Lastly, is it practical to never have a rogue in your party at all and just have, say a monk, pick up some thieving skills via cross-classing or is that too ardious and time-consuming? The reason I ask this last bit is I once did BG2 solo with a monk and it was sooo cool and I'd like to solo IWD2 with a Dark Moon Monk and cross him with a sorceror, if I get him to find/disarm traps by himself than he'll be sitting pretty! But will it take just too long at cross-classing with the rogue skills to make it worthwhile????
Anybody know the answers?
Thanks! -Bawookles

[fable]

I mean once you've put just one level into rogue you can than get all the thieving skills without cross-classing and you can build up your character in other levels of bard or fighter or whatever.

Yes, but you pay double in skill points.