The 'seat' is called a saddle, and it should be so high that your leg is nearly fully extended when the pedal is in the lower position (6 'o clock).
As far as the rest is concerned: take it as it comes, and see how far you get. If you don't already own any, get yourself some biking gloves (they needn't be expensive), and some padded shorts. I usually wear lycra cycling shorts with regular shorts over them, so I don't look like a **** off the bike
