In the end no one really knows if it will be okey for a card 5 years from now. but it seems like the card form now on will take less watt, atleast thats some story about nVidias future card and I mean sometimes it have to be enough. they cant pumping out hardware that only takes more and more.
Sure a good 750W PSU should be enough for any singel card solution in the upcoming years IMO!
Temps seems fine to me but im no pro so better listening to the other guys who knows, but I think it's all fine
And no it's not a problem to set higher fan speed to the GPU, some guys have it set at MAX = 100%
The only thing that can take damage is your ears but hey you gotta offer something to be on top