The geographical location of the actual service will, in large part, determine how you'll bill for services and where to look for a listing of rules and regs.

I've never seen an ambulance billing book.

Be prepared for more paper than you've ever seen or had to deal with - going with each claim. Documentation is the key.

The 'big boys' (Blues, UHC, Aetna, Mediare.......) are all pretty straight forward billing concepts. Check your HCPCs book for 2006 it has a great section on ambulance.
barbara