re: Poker & 4 2 rule for outs
Once you play enough and have studied the odds, you basically know what they are from your head for each street and each situation.
I would suggest people use one of the many odds calculators to repeatedly plug in hands they are involved in (or others) to get a great feel for the proper odds.
Here is one I have used for both NL and Omaha
Flush Draws are 2 to 1 against making after 'four flush' flop
Making a Set on the river is 22 to 1