Avatars and sig banners

[Rogue Hawk]

At what point can I have a custom avatar?

[Chupaca]

your avatar, as far as picture , you can change at any time as well as signature by going into settings in your profile. As for the title it automatically switches to senior member at a 100 posts. Changing that I believe is by request...

[billybovine]

At what point can I have a custom avatar?

From the moment you joined. Click on "Settings" on the top right of the page. Then chose what you want to edit on the left side.

[Bob Denman]

Avatars and Signature Line information are completely up to you.
One caveat: it's probably best to keep your avatar picture at a pretty small size... I try to bring mine down to about 220 pixels of width.
You can also add pictures and text in the signature line. again; it's probably best to keep the pictures as small as possible, and don't be afraid to experiment with them to get it right!