Stealing in Stores - Questions (spoilers)

I've recently started a game with a Jester, and now that I actually have a character with a high pick-pockets score, *and* knowing that there is a "Fence" in BG who will buy stolen shop goods i.e.

[spoiler]
Black Lilly
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I'm interested in stealing from stores, BUT I have no idea how this mechanic works e.g. what affects chances of success, what happens in the long run if you fail (e.g. as well as being attacked by everyone in sight, does the store stop selling to you for good?). Specifically:

* Does the chance of success vary from store to store?

* Does the chance of succsess vary from item to item?

Also how can I find out the base chance of success? I have Near Infinity installed, so can look things up, if pointed in the right direction.

Is it possible to steal even high value items (e.g. dagger of venom, full plate, light crossbow of speed, even stuff like a recharged shield amulet, which is not cheap) with a pickpockets score of 100 or do you need to go even higher (e.g. using potions of master thievery)?

How high a pickpockets score do you need to pickpocket Drizzt?

Any other pick pocketing/store stealing tips? Thanks!