For that matter, is Belldandy or Belledandy correct?  Keichi?  Megumi?

Belldandy, Keichi, Megumi. 

Wrong.  It's Keiichi.  Kei-ichi.  K-1.  Get it?

I never could figure out the name of Keichi's sempai, either the tall blond

biker dude, >or the big body-builder type.

The body-builder is Tamiya. I don't know the blond guy; I just personally
refer to him as "Johnny Bravo." He is, I swear to god! Watch Cartoon Network!

Blonde guy is called Ootaki.

Christopher Angel