I too came from PHP (but I'm not an old school php dev, just some
amateur dev) and I did not had trouble starting to develop my first
app with rails since I read AWDWR (and I haven't even finished the
book yet). I have to check the API very often and I get lost on some
ruby syntaxes still, but I am finding my way with no problems. All I
use is the API, Ruby Docs, this mail list and the book. Maybe a google
search if I don't find anything in one of those.
Maybe what you need is just a simple project and the will to start
working hands on? Remember, Rails is Agile Development...
About detailed descriptions of functions/methods, Rails API and
RubyDocs sure will help you on that. The way you say it seems like you
didn't "met" them yet.