re: Poker & Choosing my CG Buy-In
100bb's is standard because you can get all in fairly easily by making psb's every street - so if you have a very strong hand, you can plan on getting your stack in by potting.
Deep stacks of 200bb's allow you to play a wider range of hands for implied odds
. You're not going to be crazy about getting all in w a simple overpair - but hitting a hidden monster w sc's is going to allow you to play strongly.
Short stacks of 20bb's are basic shove or fold pf or on the flop.
BRM dictates the limit you play - how much you buy in for dictates the kinds of hands you will play.
If you're interested in more of the theory behind this, google stack to pot ratios or SPR.