Re: Firefox phones home, a lot.
The process I used to clean up was:
1: "about:config" in the FF address bar, enter
2: "http" in the search bar, all entries with "http" will appear
3: if http is in the "value" column, on the right, click it.
4: choose "modify"
5: hit backspace to clear the value entirely, go to the next
6: Over and over and over again.
Most of the values are to mozilla.org which may be for help tips, real or imaginary protection OR for "telemetry" which doesn't connote well to me.
Looking at the before and after network monitor log, before doing this FF was constantly connecting to AWS addresses usually in the 52.x.x.x and 54.x.x.x range, but others also.
I started firewalling them, but there was just too many to make separate block-outbound rules for each one. Then, when I started trying to guess a range for the firewall rule, the rule would block stuff I really wanted to see, maybe even amazon.com.
The problem is, there is no good way to match ip addresses with urls in the amazon aws system. Looking at a single address with Whois will usually only return that it belongs to Amazon, no url. Meanwhile, if you are lucky enough to have a url, it may have multiple varied ip addresses and ranges and in any case there are only one or two sites I have found that can even get you that far.
SO, I blasted away all rules with http in the FF config. No doubt many of them are truly helpful. Also, no doubt some of them are merely telemetry to spy on what you are doing.
At this moment FF seems to be doing fine, minus some help tips. I am good with that.
I remember some blog about a year ago with FF developers who addressed the FF telemetry issue. As I recall he/they took the position something like, "we are going to do it, if you don't like it, too bad".
Yes, it is too bad.
(thanks for asking about this, I would have took better notes if I knew someone was actually interested in this.)