[K12OSN] Replacing ltsp 4.0.1 with 4.2.1

[Jim Doyle]

I am now using K12LTSP release 4.0.1-1
I would like to do a new install (not an upgrade - right?) to 4.2.1 and
keep my /home.

1. Is ltsp 4.2.1 stable and the best choice at this time?
2. Can I just copy /home to a safe place and then copy it back after the
install is complete? That is, replace the /home created by the
installation with my backed copy of /home?
4. As I recall I should copy a few other directories also, but can not
find my notes.
3. Is it a good idea to have /home on its own partition (in the new
installation)? 
4. Is there a HOWTO on this subject?

Help with any or all the above would be appreciated.

Thanks,

Jim