I've GM'd or higher most of the skills you're looking to do. Here's my input.
Stealing - Jehlom docks in tram. It's outside the guard zone, so no danger of getting whacked or PK'd. Lots of NPCs around to catch you for gains. Drop items in the barrel that are 1/10th of your skill. (ie. at 60 skill steal 6 stone items, 70 = 7 stones etc.) Easiest way to train that I know of without risk of PK or having your packie killed.
Hiding - spacebar macro. That way you're using it while you bank sit and type.
Stealth - train with hiding. Easiest way, if you have a custom house, set up a teleporter on one floor with a clear path as long as you can get it directly across the plot. Walk off teleporter 1 (single left click while walking to lock your character in motion so you can take your hand off the mouse) and hit your hide macro. You will auto stealth. When you hit that 2nd teleporter you jump back to #1 and keep going. Sometimes called a stealth treadmill. With your mouse locked you just need to hit your hide macro when you fail and reveal. Add armor as you go to make it more difficult. There's a sticky around someplace with the correct armor to add for each skill level.
Lockpicking - T-Hunters forum has exact levels, but at 50 skill get a box made by someone with roughly 60 tinkering skill. Set up 2 macros. One to use a pick and target the box, the other to lock the box. If you combine them into one, you're going to unlock your box when you fail to pick the lock. As you get higher in skill you need higher level tinker boxes. Get as high as you can then around 90 skill or so get a GM tinkered lock box and head into twisted weld. Have a Satyr discord you, leave the weld to break agro then run back in and stick close to him (alt click to auto follow). The disco will drop your skill and make gains of that GM box easier, be warned, you will break a lot of picks so bring plenty.
Snooping - Easiest way is to find a guildmate who isn't busy and have them just sit there and snoop them over and over. Personally, I logged my 2nd account in on my laptop, and my main on the desktop then had my thief snoop the other account. Shouldn't be too tough to gain.
As for detect and remove trap, I've never had use for them (telekenesis scrolls on a human thief open chests from a distance and remove the traps without killing me usually) so I can't give you any guidance there.
If you need any clarification on anything feel fee to PM or ICQ me. I just wanted to hit the board points, I'm at work and can't make this too detailed right now.
