IceCat question - forced updates?

[Robert D. Bowers M.A.]

I am leaving Firefox after using that browser for around 15 years. I was 
glad that it came out because of the ability to configure it - and 
escaped from IE (then shortly after went with Ubuntu).

I have three questions that will decide whether or not IceCat is for me 
or not.

#1, and very important - can I lock IceCat so that it will NOT and I 
repeat NOT automatically update - it will allow me to choose when to 
install the update?  (I don't mind at all if it downloads in the 
background.)  I work from home and having Firefox shut me down in order 
to do a 'restart' happened once too often - and it's a regular threat.  
I've tried everything I could find to stop that behavior, but it won't 
stop, and it seems that the idiots doing Firefox won't listen and 
realize that they could put people out of work by THEIR decisions.

#2: How easy is it to migrate all of my bookmarks and so on to IceFox?

#3: I use several add-ons for protection and 'comfort'.  How many of the 
Firefox add-ons will work (or have been ported over)?

I use Ubuntu 18.04LTS, and have adequate protection on my system - and 
am careful where I go (especially while working).  However, I cannot 
have anything forcing me off the internet - I must be the one who makes 
the decision as to when updates occur!  (I would suggest updating upon 
shutdown of my system for the night.)

Thanks!

Bob