1) Not really any recommended ones. But I had some fun with the varios amos mods (or atmos, or forgot his user name)
2) CBM for some bugfixing/balancing.
3) Better/no indies. (fixes some AI issues).
4) The various awesome mods are fun.
5) See: http://www.llamaserver.net/globu/Dom3_Mods_Catalog/
6) shameless plug: http://forum.shrapnelgames.com/showthread.php?p=784948
Question 2: I have no clue.