2. I also have 2 backups in USBs (which is my pain-point). I think USBs are the worst option.
Why not add something else to the mix? Get an old HDD, get a cheap USB bracket, and use that.
4. Every 2 years, I rotate my backups to new USBs. (this step has only happened once, but next summer I'll need to repeat it).
Does "rotate" mean you get rid of the old ones? Why not just add one to the total backups?