We can add image but not avatar ?
Correct.
It's like you buy the Member rank, and avatar you can wear when you are Full Member. The difference is if you are a Member rank you need 90 merit to reach the Full Member (not taking the activity into account here as it's just a matter of time) but for a Copper Member (if you buy it when you register your account like you) you need to get 100 merit.
We need more merit if we are a Copper Member... it doesn't seems logic but ok.
I think it's hard to get 90 merit.