Permissions allow/disallow users to perform various functions, like edit bands, post messages or start new topics. Permissions can be modified by Admins and Mods. To see who's got which permissions, go here
Warnings are given to users who violate site rules and policies in any way. They come with a number of days for which you can be banned. When you get your third warning, you will be banned for the combined amount of days you received with warnings.
After the number of days expires, you get the permissions back. You can view your current permissions in your profile.