When you post there is an option to show your signature. I think it is checked off by default. That will enable the signature. As for the Avitar Edit User CP and then go to Avitar and then upload the desired AV from your picture hosting site.
“God never promises to remove us from our struggles. He does promise, however, to change the way we look at them.”
The most he did was die for me, the least I can do is live for him.