Hi, glad you like the case!
Everything looks fine, you will have to manage psu cables a bit but shouldn't be impossible. Regarding CPU cooling, only way you could install AIO with such a large gpu would be by using 120mm aio with 92mm fan on it (I can provide the fan adapter).
Best or largest air coolers that fit N-ATX are:
[URL unfurl="true"]https://noctua.at/en/nh-l12s[/URL]
[URL unfurl="true"]http://thermalright.com/product/axp-200-muscle/[/URL]
[URL unfurl="true"]http://www.cryorig.com/c1_us.php[/URL]
[URL unfurl="true"]http://www.phanteks.com/PH-TC12LS.html[/URL]
[URL unfurl="true"]https://www.bequiet.com/en/cpucooler/570[/URL]
[URL unfurl="true"]https://www.scythe-eu.com/en/products/cpu-cooler/big-shuriken-3.html[/URL]
[URL unfurl="true"]https://www.zalman.com/EN/Product/ProductDetail.do?pageIndex=1&pageSize=10&productSeq=322[/URL]
So you can look up for some benchmarks.
You do not need any case fans indeed! All components have access to fresh cold air and can efficiently exhaust warm air. You could maybe add an 80mm fan on top if you cpu temps are too high, but I think it will be fine without it.
Yes there is, a nut that holds the case together so it is a real mechanical block.
