Unfortunately most of this is out of your hands now. There are a few things you can check for, and then you’ll have to just get on with your life.
Free information on the web isn’t free; there are costs to provide it. Pop-ups: advertising, offers, and social media, are all part of the “cost” of free.
As you’ll see, website-browser compatibility is a bit of a mess. The solution is just what you suggest: have more than one browser ready to go on your computer.
If an ad claims that they will fix your computer for free, be skeptical. You know they are trying to make money, and besides you may be able to handle the problem yourself, for free.
When a hacker gets ahold of your computer they can do anything. Keeping them off is the best plan.
It’s unlikely that you’ve been hacked. It’s possible that your friends have both been hacked, but this kind of thing can happen without anyone being hacked at all!