1. To become a moderator, you must be a helpful, upstanding, clean member of Spiderweb for a long time. When a moderator spot opens, a member who has the above qualities is selected to fill the position. Chances are, newbies like us will never become moderators. I have no idea what you have to do to become an administrator, but as far as I know, Spidweb and Drakefyre are the only administrators the boards have ever had. Since Spidweb (Jeff Vogel) only pops in about once a month to comment on the BoA boards, Drakefyre is the real admin.
2. The "ratings" below your username are titles which are based on your post count. From the FAQ:
0-50 posts
Apprentice
50-100
Journeyman
100-250
Citizen of Exile
250-500
Adept
500-1000
Erudite
1000-2000
Veteran
2000-3500
Guru
3500-5000
Frolicking in Postland
5000-7500
Postmaster General
7500+
Your Postliness
There are also custom titles, and there are lots of topics with information about them, so I won't explain them here. I'm not too sure I understand them myself, anyway.
Welcome to Spiderweb! Don't spam, use good grammar and spelling to the best of your abilities, and only join the RPs if you're the responsible, enduring type.
EDIT: Also, ignore Scorp.