Are they one use? I was reading the cards tonight and it seems like they are in the description, but I've seen people use them multiple times.

What makes you think they are, the exhaust part? Look up exhausting and unexhausting (refreshing?) in the rules manual. Cards and tokens that are exhausted become refreshed and able to be used again at the end of every round.

Yes, the "exhausting" part of the card description made me go that way. I hadn't even seen the section of the manual specifying what that involves. Thanks!