Constant scouting is the key.

If you see 6 pool, prepare the block your ramp or his. If you see gas and noting else in his base, prepare for reaper rush, if you see mining probes with nothing or forge, it's canon rush. It's very easy to spot these cheese but if you don't scout, you'll end up beaten by those cheesers. However, if you manage to stop these nonsense, the game is 99% yours.

You have so much time to check every single troop you have by entering and exiting bunkers, why don't you spend more time in attacking your opponent instead?

Starport for Medivacs, so MM bio ball gets heal. Or vikings, etc. Is that what you asked?