Need help

Wow $1465, the price jumps! Up $350 on a year ago, up over $150 this month alone. What a horrible time to buy.

what I can and can’t upgrade
You can upgrade everything in a PC, but you probably won't want to change out the motherboard or CPU. I don't see the PSU in the specs, hopefully it'll be strong enough.

You should have enough RAM. The disks depend completely on your usage, but should be fine. Keyboard & mouse are also subjective.
I’m buying
If you haven't bought yet, have a look around. That looks very expensive for what you're getting.