It does not break.

It just becomes weaker for some minutes.

No, 8-8 meant that the level for this dark zone is between 8 and 8, so only players with level 8 are put into this zone.

If you are in a group, you can of course join your team mate’s dark zone. If you are level 8 and he is in a dark zone level 1-7, you can’t join him. But he can join your dark zone level 8-8.

So far…