I'm a little confused on what you are asking, but I will try to answer based on what I think you are asking.
1) Yes, each mode has an oxide group that gets created for it. Normally with oxide groups, players can be apart of multiple groups. However, WarMode makes sure that players can only be in one mode group at a time (it will forcefully remove other mode groups when you join.) So if you are in the warmodepvp group you cannot also be in the warmodepve group.
2) I really don't know what you are asking here. With default settings, PVE players cannot raid other bases and no one can raid their bases either. However, in order for a base to be marked as PVE, all the players authed on it need to be PVE. If there is even just one player authed on it as PVP, then that base is considered PVP and can be raided.