I have a similar build to yours and i use Cooler Master 750w and it is working fine. I would suggest using 750w for future-proofing your build. The after sales support of cooler master is quite good too so keep that in mind.
I think Logitech MX master 2s is a good option ergonomically but if primary concern is gaming then you should go with g502. There are other options like razor orochi v2 and hyperX pulse.
I would suggest buying the LG one. Not only it is beating acer one on refresh rate and response time you should also have to think about after sales support where LG beats acer quite easily.
I would suggest going for realme Narzo turbo 70. I just bought it for my mother after exchanging her samsung with it. I think this is a good phone in this budget. Go for 8gb variant, the camera quality is good and the ui is smooth.