So if you go to your Admin Panel there is an option under General Settings for Custom Fields - Character.
You could create a field for "Raid Team"
Make it a drop down box and add the Raid Team names.
Then select "Show Field on the Roster List?" as Yes.
This would make a field that would display as like the last column on the Roster for your site. The Challenge here is that you cannot restrict the player from editing it. But it does allow people that have admin rights to update Character Profiles to set them. This at least could solve the problem of how to display the characters Raid Team status and easily see who is on what team.
Another alternative would be to create a Custom Menu and include the team rosters are part of that or maybe as a Guide which in essence is just a separate HTML or BBCode page linked from another part of your site.
As for recruitment you can use the build in recruiting module for that. You have to create a new application called "Raid Team X" and then just the correct permissions. Set this so that the only guild members of the appropriate rank can apply and only Raid Leaders of the appropriate level and view and approve them. You can set up some other things depending how you want to handle it. I did one once for help just managing the site. I posted openings for Forum Mods, Recruiters, and such.
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Six Demon BagJack Burton: Hey, what more can a guy ask for?
Egg Shen: Oh, a six-demon bag!
Jack Burton: Terrific, a six-demon bag. Sensational. What's in it, Egg?
Egg Shen: Wind, fire, all that kind of thing!