One of the best things for R is the mailing list. At leasr when I was learning stats and R rhe knowledge both of how to do stuff in R and what math to use when was phenomenal. If gentle people didnt answer in time Prof Brian Ripley from Oxford would answer early morning British time and explain why your question was wrong and what the math meant and what you really meant to do and why and then 3 lines of R to do it.