Not sure about 2; but I want to focus on 1 first.
Have you created the groups using ULX for the custom groups?
You must have ULib groups already created, which can be done in two ways.
2) Through ulx addgroup (then adduser) command, or, /settings/users.txt, the standard default GMod way of creating groups/assigning people to those groups.
Also, if you've used the users.txt file for gmod, you can't have them in more than one group, even using ULX. They'll always be assigned the lowest group from /settings/users.txt
UTeam has no effect on actually creating the groups. It only reads what ULib say's they're in and assigns them accordingly.
Off the top of my head, it sounds as though you have some people listed in more than one group.