Welcome to Gaia! ::

We've actually had a Goblins thread before, and a few of us read.

Books that I own for PC purposes: Player's Handbooks 1-3, Adventurer's Vaults 1-2, Martial Power 1-2, Divine Power, Arcane Power, Primal Power, Psionic Power.

I'd possibly skip on AV2 though, unless you want it for those implements that benefit classes that were released after AV1.

There is no above 30 for PCs, monsters can be above level 30. Each Epic Destiny gives ideas for what happens after level 30, usually discorporation, ascension, becoming a force of nature, or founding some school of doing what you do. Typically your character becomes a background anchor for your next character. "Man, I always looked up to Frank the Black after he saved my family and became a demigod. That's why I've taken the name Jim the Black."

I recommend all of Rain's books as well as Forgotten Realms Players Guide and Eberron Player's Guide(and likely Dark Sun Campaign Guide though I haven't spent much time with that). They contain lots of great material for any campaign unless that campaign is run by Rain Yupa, and the new classes and races are even supported in the Power books that follow them.