Looks like a decent gaming setup. You'll want a better power supply though. A 600W is the minimum recommendation for a system with a 3060 GPU. If you want to future proof it, you should probably go a little higher than the suggested bare minimum. Don't go small on the case.
As for monitors, it all depends on how much you have to spend. For current gaming, a good average monitor will be at least 1440p(2K) resolution and 120-144Hz refresh rate. Get the size you can afford.
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