If you are second-guessing about the CPU, you can't go wrong with the 7800X3D. It is more expensive yes, but also a beast. With that you don't have to upgrade for many years.
You have 64 GBs of RAM. 32GBs i more than enough, unless you do heavy video editing or other reaaally professional stuff. You should take 32GBs and use that money for better CPU or GPU.
I have been using Nvidia for a long time and haven't had time to get into AMD scene, so I really can't give any input on your choice of GPU.
Water cooling is not necessarily better than air cooling. Check out this video by JayzTwoCents for input: https://www.youtube.com/watch?v=RQ3c0kspOb8
Be sure to buy a fan for rear exhaust! I didn't see one preinstalled in the case.
And lastly about the monitor. You probably could get a cheaper FreeSync monitor. Be sure to check extensive reviews that test all aspects of the monitor. That means no reviews from PC Gamer etc.