Tini Update: Deviantart Group Roles and Folder Limits
Finally got an answer to a question I've had for a while now, with definite numbers :D
Groups Roles
There can only be 100 admins in a group at a time, for example 1 Founder and 99 other admins, though didn't specify if there was a limit to other roles atm.
Gallery Folders
160 folders and 250 collections, so that's a hella lot of space so I'm good on that XD