Listen to BoostedBMW's post. He speaks the truth
Broscience 4tl. As far as your original question, read this post:
http://forum.bodybuilding.com/showthread.php?t=272067. It will answer all your questions about pre/post workout nutrition.
The only thing I'd like to add is once you figure how how many calories you need per day, it tends to be easier to break them down into 'macros' (nutrients needed in large quantities). Keep in mind this isn't exactly "required" per say and the breakdowns you use are totally up to you, but it makes figuring out your general daily caloric intake much easier.
Personally I'm a fan of 40/40/20. For me it's a good overall macro that I can use to both bulk and cut. Basically, 40% of my calories come from protein, 40% from carbs, and 20% from fats. Also...
1g protein = 4 calories
1g carbs = 4 calories
1g fat = 9 calories
If you're attempting to bulk and your maintenance target is 2500, you need about a surplus of 500 calories as Boosted mentioned. So, assume you chose to use the 40/40/20 breakdown, here would be your daily values (3000 calories):
1200 protein
1200 carbs
600 fats
And here are those values in grams:
300g protein
300g carbs
67 fats
If you feel you can't consume that much protein per day, you can do whatever variation you prefer...30/50/20, 30/40/30, doesn't really matter because there's no one 'best' macro. Just make sure you have enough protein =) And you can split those values up however you want into as many or as little meals as you want.
Btw, after you loose large amounts of weight quickly, it's quite common to have to have a combination of loose skin with fat underneath the surface...aka skinny fat. It's a bitch and there's really not much you can about it at the moment (unless you want to consider a tummy tuck). Personally, I'd recommend a nice LONG clean bulk to fill out your frame, then try cutting again.