I have never used the pickpocket skill before, so I have some questions:

1. Is there a max no. of times that you can use it on an NPC & still get stuff?
2. Is there a max no. of items you can take & how is that affected by pickpocket skill level or by player level vs. NPC level?
3. Is the ability to pickpocket high quality/expensive items affected by the pickpocket skill level & if so, how? Is this affected by the player level vs. the NPC level?
4. Does it make a difference if it's a merchant vs. a non-merchant NPC you're trying to pickpocket?
5. Does leaving the area and returning make a difference? eg: does porting in & out of the Battlefields allow you to pickpocket additional items? If so, is there a limit to how many times you can do this, or how often?
6. If you increase the pickpocket skill level, does any of that change?
7. Anything else I should be aware of?

6. yes, each level (from 1 to level 5) of the Pickpocket Skill 'mentioned' the LEVEL of the NPC you can pickpocket safety, but if you try to pickpocket a NPC of a higher level he/she will notice you and become angry with possible consequences ... .

With the skill "Know Creatures" you can "see" the level of NPC's and enemies. Read the description of that skill if you wish to know more about it.
There are also equipment items to find/buy which have a boost of 1 point to this skill (handy if you only wish to TRY the skill, but not invest points in them)

Further on I never really used Pickpocket, so I do not know if the "inventory" of NPC's after a while are back filled with items, but I believe if you picjpocked an NPC you can take all his/her items.
Try it if you like it .

Thank you much, that helps. As far as pickpocketing again, I wasn't concerned with whether their inventory respawned, but whether or not I could finish emptying it. When I tried it before I posted the message, I was only able to get about a third or perhaps a half of the items in the NPC's inventory (I tried it on the Riddler & on Annabelle in BF's). Since I had used up all my spare points to get that much, I'm not sure if I can get more if I add more points.

And items with pickpocket skill? Wow! ... I either have not gotten any yet, or I've not noticed it. That would certainly help reduce the no. of points I have to invest in it ... just keep them in inventory till I need them.

The level and number of items that can be pickpocketed is determined by the level of the skill, but I never used it myself.

I got a couple items with Pickpocket bonuses in Divine Divinity, but never noticed any in Beyond Divinity (though the skill isn't needed for any quests, etc, in BD so I wasn't specifically keeping an eye out for that bonus).

Ah, ok. That makes sense. I think I'll run some tests.
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Ok, ran the tests ... it's
I need to generate some skill points.

Sorry Allana, I was confused with Beyond Divinity vs Divine Divinity ...