I can answer the last two for ya...lemme log on myspace really quick...
*type type type*
Alrighty, for the addition of John to your friend's list, go to his page, and see the square underneath his display picture on the left side? It's headed as "Contacting John Mayer". In that box, click "Add to Friends". It's the second one down in the left column. Then myspace will ask "Are you sure?" or something like that. Of course you are!
Now, for the editing for your space, there are a lot of sites that offer layouts. The one I recently used is
http://www.whateverlife.com - they have premade layouts that are really cool! Pick one you like, copy the code, and place it in the "About Me" section of your editing place on myspace.
Hope this helps!