OK, I've read it over....
First off, I don't like the "one guild per world" thing. Not only is it improbable, but it eliminates any high level politics. Unless, of course, the leader of the WWG (world-wide guild) is an interesting character.
Thieve's Guilds (esp if WW) should be setup in a cell-like structure. The idea that non-members would be brought before the Chiefs won't work. You probably want to combine the Beggers with the Swindlers and the Fences with the Smugglers. Both groups have too much overlap. Not every begger should be a member, just a few. The rest should just be "shaken down." Similarly, the Thug branch should handle the security and enforcer type stuff. Spending most of its time keeping the members in line. Maybe there's a basic non-member shake down fee (25%) which is worse than the member cut (10%). That way, theives will be trying to enter the guild rather than be forced to.
Let me know how the sample turns out.
Aaron