^^^
That,
for one.
Sparkfun should have some info too. (If searching, I find that adding "cadsoft" to the search string helps. "eagle" easily confuses search engines.)
2) eaglecentral.ca is a sizable forum for EAGLE. Search around there.
3) Your board manufacturer may have requirements for their Gerbers. Check their website to see if they have a listing of them.
4) Some board manufacturers will take EAGLE files directly, without the need for Gerbers. They'll need additional information though, which isn't present in any of the files: Soldermask color (green is most common, and usually cheapest), tin/lead or lead-free tinning, silkscreen color, and possibly some other details, depending on what you're making.
5) How long have you been using EAGLE?
6) Font on the forums....do kindly keep it at a normal size.
7) Dear god, don't forget to do the Design Rule Check.
I usually use 16mil clearances for all Different Signals in the Clearances tab. That's pretty big though. 12mil should be fine, or maybe 8mil. Bigger clearance = easier to manufacture = less risk of scrap = lower cost (usually). If you go in with 4 mil clearances or tiny traces, be prepared for some serious upcharges.