1) First number is frequency, second identifies the set it belongs to.
Set IDs can be referenced here:
http://www.ootpdevelopments.com/boar...d.php?t=120862
2) You can't. If you alter the names data, it will alter it for all leagues, but only for universes that are created after you have edited. Pre-existing leagues will not use the new data at all. This maybe (hopefully) will be changed in OOTP2007.
3) correct, "names.txt" is for surnames.
More info on all these topics in customization guide located here:
http://www.ootpbaseball2006.com/down...=download&id=4