Are you planning for SLI? I ask this because 750 watt is really really really not necessary. 650 is big enough.
Noctua coolers are really good, but you can also get good cooling with 212 evo.
90% of the g1 gaming cards indeed have coil whining. So if you want to play with noise get the g1 its a really good card. You can also wait a few days longer and the gtx980ti lightning.
The strix is also a good option.
I wont trust wiki. Everyone can type what they want there.
SLI and CF is a technology used for gpus.
So you can run multiple gpus. In one game its more optimized than others but indeed it will be used 50/50. (not in all cases).