6700(xt) are at much better prices now. You have a lot of options for cpu, pretty much depends on how high you want to go. The high end Zen 2 cpus might need a newer motherboard. Put whatever you end up deciding on in pcpartpicker and it'll give you a wattage estimate, the main thing I would worry about for psu is gold rating from a well known brand. All of the Zen 2 prices are good, it's really just a matter of how high you want to go and if you're willing to upgrade your motherboard if necessary.

If you get an aftermarket cooler, get this. It performs pretty much as well as a high end Noctua but for around half the price.

I would look at getting 32gb of ram sometime unless you've checked and definitely don't need it for anything you do.

Generally, productivity things benefit from and utilize more cores more effectively. Some games use more cores well, some don't. Some exceptionally shitty ones won't use them well at all and will pretty much need strong single core, ie 5800x3d. I wouldn't worry about it unless you specifically know something you do falls into the last category or if you have a productivity hobby.