Hm, I think that’s not correct: you should be able to read (and write) your old repo with the most recent version of restic.
We’ve recently (in the Git master branch, not released yet) added code for a new repository version, but that’s strictly opt in, older repos will just be read and written just as usual.
You can work around that by initializing the new repo with the old chunke/deduplication settings (via restic init --copy-chunker-params.
Yes. See here: Compression support has landed in master! - #8 by MichaelEischer
Likely you can do that. It may happen that your kernel is too old for the version of the Go compiler and runtime we used to build the binary though, but it’s not dependent on any library that comes with Debian.
That’s the safest way for sure, but you don’t really need it unless you want to try the new compression code. Otherwise just use a new restic version and keep using your old repo. 