Ok then guys, christmas has ended and work has recommenced.
Thanks to the responses I'm feeling quite confident with these questions now, however one question I do have is about the example question.
Rather than just working out the answer for oxygen, would I be correct to divide by 32 instead of 16 if it where o2 and not just one oxygen?
Also if I wanted to do this for a compound like water, would I just add all the atomic weights together and divide by the number of moles?