I’m not at a computer to verify, but dpkg -I package.deb will list dependencies of a deb file, so apt-get download $(dpkg -I rescuezilla_2.4.2-1_all.deb) might work.

The answer to this is going to depend on your raid controller. Frequently the answer is yes, but some raid controllers are more particular about exactly what drives are in the array. Software raid controllers are typically more forgiving of this type of change.