I don't have much time so I will leave you a bit of information that might help you. Most of the answers you are looking for you can figure out by looking at the code in the datamanager. Take a look at "class_dm_threadpost.php".
1. signature - You will find the answer in that code. (This one is easy.)
2. no wiki that I know of.
3. floodcheck - It might be possible to shut this off by fooling the registry and restoring it after your code is done executing. Again look at the datamanager, the answer is in there.
if you send me or post your code ( so I do not have to recreate everything ), I can give you a quick hand with your questions.
Take Care and Good Luck.