Excluding files from snapshots

I'm sorry if these questions seem uninformed. I just reinstalled Windows and don't want to do anything that will screw up the system.

I'm trialling FD-ISR and just made a secondary snapshot after having installed but not activating Returnil.. This snapshot includes Returnil image files and so the snapshot is quite large. Perhaps , i should have taken a snapshot before installing Returnil.

Should the Returnil drive be dismounted to prevent its Windows image files being copied into the secondary snapshot.

Is it OK to make a snapshot with a system with Returnil installed and how can i exclude files, such as Returnil files, from a snapshot?

I understand that the snapshot is bootable. Must it be placed on drive C or can it be placed on another primary - or perhaps an extended - partition (one not containing the OS)?

I read that I can create an empty snapshot on which i can load a bootable OS.

Normally you have to install the later OS on a system with the earlier OS already installed. Using FD-ISR, can I install Win 98 to an XP system via
FD-ISR?