All CPU nowadays will be x64.
Everyone else will have good advice on that particular setup, but a cursory look seems like it'll go well together. Personally, I set a budget and a goal (I want to play X game at 2k @144hz), and go from there.
Also, might be worth looking into monitors to compliment your new hardware (like 144hz, HDR, and other stuff).
as far as PSU goes, i'd say bare minimum of 500watt, but I'd feel more comfortable with a 750watt. do a gold or platinum if you want your electricity bill to not be crazy.