My b2evolution Version: Not Entered

As a consequence of my other recent topic about admin problems, I think about update to latest version.

I have 3.3.3 today. Can I just install 3.0.8 above it, and all posts and comments will remain after it?

(My web provider offer 'Installatron' application to handle it with, if that is interesting)

I have done backup files, and a additional question can be, if the 3.0.8 can import/read the backup from 3.3.3?

Kind regards
Tyrone