If we're talking about direct replacement then If you don't do data-intensive work, there won't be much benefit, though down the road there may be some with direct storage.
If that's your main drive, changing from crappy QLC to TLC sure wouldn't be bad thing.
Having done similar, I saw no noticeable improvements outside of benchmarks.
Probably not unless you need the extra space and are upgrading for that.
Be careful of the big drop off in QLC performance when they're getting near full, the cache space drops off fast and they're really slow to write to when the cache is exhausted.
SN850 is a top tier drive and there's been some good deals this week.
No issues but you may as well save some cash and get a Gen 3 drive for half the price.
Should have mentioned that your board was only Gen 3 .