Headliner Installation '72 Duster

Not that I'm at that point yet, but I hear that this is really a *****. The PO took the original out along with the rest of the interior, so I have no idea how this is done. So, on with the questions:

1. Is there a difference between a headliner from a '71 vs. a '72?

2. Can the headliner be put in after a roll cage is fitted or does/should it be done before?

3. Is the headliner installed before any of the other trim panels like the sail panels are installed?

4. Am I better off farming this out to someone who knows WTF their doing? lol.

My knowledge of interior/upolstery work is limited so please keep the flames down to a dull roar. :-D Oh yeah, it appears that the PO left me the headliner bows.