Mac OS and Carbonite experience? Mojave->Catalina, iTunes->Music, dead computer

My 2012 27" iMac croaked unexpectedly. I THINK have 3 different backups, but having turned into a geezer over the last 8 years, I'm not sure that I know how to proceed. But lucky enough to have acquired a 16" MacBook Pro.

Question 1: Does my iCloud backup of iTunes/Music include recordings I had made and inserted into my computer's music library that are not available commercially on Apple Music (to which I subscribe)?

Question 2: I have Carbonite, but have never had to use it before. Can it restore my iTunes/Apple Music library into Music on the new laptop?

Question 3: An auxiliary bootable drive backup of Mohave just a couple of weeks old should also have everything. Can I target just the stuff I want for backup from that drive, or, given that the change from iTunes to Music happened during the time my iMac was dying, would I be better off replicating the backup drive on my MacBook Pro and then again updating to Catalina after that?

So many options. So many technical issues for a mind succumbing two or three neurons a minute to standard dementia. This stuff has grown difficult for me to grok and to act upon...

All pity, help, reassurance, and links to help accepted.

Thanks