All Tangs? Yeah, pretty much, your tank is too small. They need a lot of swimming space that a 65 just can't provide. I'd stress that this is particularly true for any of the Acanthurus Tangs. The only Tang that would even come close, IMO, would be the Kole's Tang, but even still I think the tank is too small.
On Flame Hawks, all individuals are different. There is a risk, however small, that it will go after shrimp, snails, hermits, etc.