I'd call items as a plot ticket, basically something that if you break it its gone for good and will generally serve as an ace in the hole. Got a frigin awesome car for a getaway? It most likely you'll trash it in this process. Basically: Items are not stuff with a recharge time or drawback other than the amount of time it can be used before it's turned to shit.

As for powers, I say about as many powers as you have drawbacks with me looking through them for validation first to see if it balances.