There is no such thing as a crank case drain nor are there any deposits you'd want to drain if there were such a thing. Perhaps your frind ment the transmission oil and drain. The transmission drain plug is on the botom of the engine and should require a 14mm socket. I normally change transmission oil every race or every other trail ride. You can use motor oil (10w-40), bike specific gear oil or ATF (I use Dexron III ATF myself).
There is a rubber fill plug on the right side of the engine and the oil capacity is cast into the right side case as well.
Don't worry about whatever the mags said about the bike, their opinion is typicaly not very objective and even if it were it would have very little bearing on your specific needs, conditions, perferences etc. You can be certain that the bike is far more capable than any non-pro level rider. The general consensus is that your CR was slightly behind the others in the engine department, but had better handling, suspension and brakes than the rest.
You should also oil the chain, clean and oil the air filter (only use oil designed for dirt bike air filters, I recomend bell ray filter oil) every ride or every couple of rides depending on how dirty it gets.
You should change antifreeze about once a season as well.
good luck and have fun.