Also, I just looked at our page to verify. The clans (which are limited to 100 people each on XBL and psn) are full, but you are still part of the group. We have auxiliary clans we created to expand the number of tags we can offer, so we can help direct you to them if you'd like.

Only if you check the box in the pop-up. You can join the group and not be in the clan.