No. I had Ryzen 5600 and it was working without problems with stock cooler. So your CPU should be fine. Replace thermal paste and you’re good to go.

Depends. If your laptop knows flex mode. First your laptop might have soldered RAM. Either way if it came with 4gb it’s kinda old laptop? Check even if you can put that much RAM in it. Never tried to exceed maximum ammount. Will it work but on your own risk ir it will not even recognize.