The upgrade you have planned to go from 24 - 32 for your ram is not worth the money. Anything over 16 is useless when gaming. Their are plenty of benchmarking videos that show resources used and performance at various levels of ram. 16 is still overkill for all gaming these days and likely won't change anytime soon. Spend that money on something else or save it for a new build in the future.
8000 benchmark isn't bad, and I believe that still scores you an Extremely High score according to the benchmark. That should be enough answer for you that your system at 4k will still perform quite well in most situations.
I believe a PPI / Pixel Per Inch of around 110 is the desired ratio, but it ultimately comes down to preference. Your 4k 43 Inch TV is 102.5 PPI which if you notice things being a bit too small, it's because of that. If you find yourself scaling the UI, Fonts, etc... to be larger than running 4k is a waste.
My advice and please note it's just advice. Don't move forward with your upgrades at all. Save the money for building a new system in a year or two. What you have will play FF14 at 1080p or 4k well enough to enjoy the game.