If anyone is curious - I was able to flash from the first version of the official Nougat beta posted in this thread, which I've been using for the last couple of months, to the final version of 7.0 released a couple of days ago. I flashed the BTU (UK) version, flashed those files with my HOME_CSC (TEL - Telstra Australia) in the latest Odin. It kept all of my data and settings (I thought I would have to set everything back up again) and the phone has been working 100% fine. I'll wait until Telstra releases their official 7.0 firmware then I will flash to that and I believe it should keep all of my settings and data and I'll regain OTA updates.
Oh speedy.. Nice to see You in my thread. And so far no. My friend tried to flash TWRP and somehow he fell into a bootloop. I will try to root it too and then tell You if it works! But probably it won't. We need someone like geiti94 or chainfire to get root to work.
Whole SystemUI is new, camera app is new, apps are new, keyboard is new, browser looks different too, InCallUI is different, AOD is interactive finally, 3rd party notifications work too, notification design is also new, there is performance mode like in MIUI that gives Your device extra boost, fingerprint scanner works a lot faster and finally it's crazily accurate with only one fingerprint scan. Any questions? Just ask me!
Knox stays 0x0 99% (unfortunately no one with knox 0x0 flashed it yet)
S-Health doesn't work because it needs to be updated by samsung.
Those images are downloaded straight from Samsung so they shouldn't change knox. But even while flashing stock roms from sammobile there's a risk that Your knox might change for no reason. Why? Because electronics aren't diamond stabe. They have some weird random issues sometimes. But it really shouldn't change knox, after flashing those my download mode says Samsung Official, so 99.9% it won't affect knox .