In IPB you can put in names which are reserved and cannot be used by members. Go into you ACP and look for the Banned Names section under Users and Groups and in the area called Banned / Reserved Names enter names and variations of names you wish to reserve/ban from member use.
Yes you can. And as well use the terms Admin, Moderator instead of usingthe abreviations. Why? What if a person uses a name that is legit but contains the letters mod or adm?? The filter would ban those names as well if you used wildcards. Best to be specific and not have some choked members.
Examples of possible banned wildcard names: Modern, Admiral
Once the member name is created before you add the filter, you have to delete it for the banned names filter to work correctly. Just adding the names to the filter does not delete or remove names already registered. It only blocks new registrations of those names.