The powers you receive with daily bonuses, the coin wheel or raffles will be added to your list. So 6/5 in this case.
The daily bonus doesnt stack, only the gits you get (coin wheel, raffles, from Fizzer) can stack over the limit. If the daily bonus gives you a powerup have more than 5 of, you need to use it instantly.
The question is what will happen if you get a powerup you need to use, but cant use (no mines/merc camps/markets). Fizzer might as well have coded it so that you just dont get these powerups if you dont have the buildings to use it on.