How many cals you eat really depends on your own body.  I can eat about 4000 cals a day and put on some good size but if i eat any more I start to pack on excess fat, I know guys who can eat 5000 cals a day and still have trouble gaining weight. Experiment and find out what works best for you.  I try to aim for 2 grams of protein per pound of body weight.
M18