How are the temps under load? you could be getting thermal throttled, everything slowing down because of too much heat.

You always want to use the GPU over integrated graphics. Only issue is more power consumption so if you are using the battery on the go and need it to last longer, switch to integrated graphics.

uBlock stops a lot of malicious websites. It has saved me a few times when I have to go on sketchy sites. Also, make sure to set up system restore points to create every couple weeks or so. They mess up, you revert them to an earlier time.

Sounds like he made a windows installation on a second partition which took away hard drive space from your original partition where your first windows installation is. If you get a partition tool like gparted(it’s free), you can wipe that partition and add it back to your original one.