Hello Frederick,
What you are quitting the wonderful world of CMOD? My heart is breaking....
Well, I will try to answer your question as best as I can.
as Justin said, "arsdoc" is the way to go in order to have a non painful migration, you will have the index file on one side, and the document on the otherside, and then you can do whatever you want with it (parse and store it in another ECM product).
Now, you are asking lots of question about CMOD backup tapes.
What are these backups? This is the backup of the database? Offline backup of migrated tables in CMOD?
Without that answered it is difficult to answer you.
If that is the normal CMOD Backup, then what you have in there, then it is the database, and in that case if you restore it, you will overwrite your current database with an old status, and you will loose data.
The more specific your question is, the more we can help you.
Sincerely yours,
Alessandro