Looks good.
Though the xeon is probably a bit overkill. Might be worth swapping for a higher clocked mainstream SKU. Though I understand its a prebuilt so dunno if its possible to swap that and the mobo out.
I’d also suggest an ultrawide panel rather than anything under 40’’ in 4k. The 21:9 aspect ratio is infinitely more useful.
As to GPU brand - any really as long as the cooler it has is half decent.
All of the GPUs use the same GTX 1080 chipset, so they will all perform the same. The only question should be if you get a blower style(only exhaust is out the back, keeps pc case cooler) or an open fan version? Best of luck!
They don’t. Branded 1080s perform better than reference because they have better cooling and higher clock speeds. So get the branded version. IIRC the ZOTAC brand currently has the fastest 1080.
Also, the xeon does not make much sense. You can get an 8 core Ryzen CPU for the same (or even lower) price and twice the performance (8 cores/16 threads). Also, the motherboards are cheaper.