Hi jimbir, where do the suggested pages appear?

If you mean on the built-in Firefox Home / new tab page, this article describes where you can turn various sections on/off, expand or reduce them, etc.: Customize your New Tab page to hide or display content.

Was that it, or was it on a website, or somewhere else?

These pop-up while I'm scrolling through my Facebook page.

Oh, are they really a kind of ad? There might be add-ons that clean up ads on Facebook. You could start with a more general purpose ad blocker and if that doesn't work, look for something more tuned to Facebook. For example -- note that I haven't tested these:

• uBlock Origin: https://addons.mozilla.org/firefox/addon/ublock-origin/
  Community subreddit: https://www.reddit.com/r/uBlockOrigin/
• Social Fixer: https://addons.mozilla.org/firefox/addon/socialfixer/
  Feature information: https://socialfixer.com/features.html

I've seen ads pop up but these aren't advertising anything. I will try one of the ad blockers you suggest above. What do you use?

Since I only use Facebook about once a month, I just try to ignore their B.S.

I do not use an ad blocker in Firefox on Windows. In daily browsing I find that the NoScript extension blocks most of what I don't want to see, and more. In my view, NoScript is for paranoid users who prefer frustration to surprises; it's not for most people.

In Firefox on Android, I recently started using uBlock Origin to preserve my sanity.

I looked at a lot of ad blocker add-ons and they all ask you to give them permission to mess around in your browser. That lights up my paranoia nerve. What's your opinion? Is there any real danger to allowing this permission?

I think it is very appropriate to be nervous about extensions that require a lot of permissions. I try hard to avoid that, but it's not always avoidable. The best blockers intercept the response from the web server at an early stage before the page has even loaded to modify the server's instructions to Firefox. Waiting until the page has loaded and then clicking a button to clean it would be far less effective.

But since I don't know if suggested for you stuff is an "ad" you could do a little more research before installing an ad blocker.