LOL, it's a cat playing with a ribbon. I like cats...
The "ranks" are based on the number of posts you have made.
You can change your pic in "edit profile" at the top of the page. Then you choose "change your avatar"
I'm not sure if there is a thread that is a summary. The threads with the most posts or the ones that are pinned (or stickied) are probably good places to start.
The lenticular shape makes ground handling easier. It is not effected by side winds as much. A traditional airship will be both pushed to the side and rotated by a crosswind. A lenticular airship should reduce both of these, especially the side movement. http://smallblimps.lefora.com/2009/07/16/the-lenticular-debate/page2/#post23