Blue Pot + Blue buff for your CDR while you rush pure AP items first instead of getting an early CDR item and then building pure AP. It's less cost efficient, since you're blowing gold on something non-permanent, but it gives more power on demand so it, in theory, balances out.
Though, I wager the confusion is because of the terminology. "Blue Pot" and "Red Pot" refer to their respective Elixirs, not Mana and Health potions.
Edit: Basically, I should have said Brill Pots or Blue Elixirs instead of Blue Pots. Just used to calling them Red Pot / Blue Pot.
Is there some kind of trick to control which part of the minion wave gets hurt? After doing several coop games and refuse to do anything but CS, I noticed that I can miss CS simply because the minion is way too far. I don't want to get blown up trying to get that gold.
Run ahead of the minion wave and take aggro early. Lead them off to the side a bit as they follow you. When they retarget your minion wave, they'll collapse on the same target as opposed to colliding and spreading out evenly (or semi-evenly).
Edit: Just to add, this is more for getting their wave to push down yours a little faster but it also means putting their minions in a better spot for you to get to eventually. It's more for prepping how the next few waves will play out instead of the current wave (which will tend to be in a worse position for you, depending on how you lead them).