Long time reader - first time poster.

I have been playing online with moderate success but with limited bankroll. Currently saving for PokerTracker (I know it is only $55 or so, but after having just bought a house - I am tapped) so until then I have been going over my hand histories by...well...hand.

Using a spreadsheet to go over each hand, I am able to catagorize many different areas of my game.

My questions are as follows...
1) IYO, What are the most important stats to keep track of?
2) What are the formulas used to get those stats?
3) Can this information be taken from you basic hand histories?

I hope that sometime in the future (maybe around 2017) I will have but a fraction of this nice bankrolls that you regulars speak of.

Thanks in advance.