Annie:
I feel your pain! We just did an upgrade to 2.2 on a system we'd been bringing forward since probably about 1.4.
Whether your "restore archives" is a good idea (it certainly will work, up to a point -- see below) depends on how big your site is. We had probably 20,000 registered users and something like 2,000 course shells, so that approach was simply not our idea of a good time... (!) Here's what we did.
- We created an "opt-in" procedure for identifying courses to retain (we notified all teachers, told them if they didn't let us know, their course(s) would not be brought forward).
- Any course not identified in #1 was deleted in the weeks leading up to the upgrade.
- We ran a fresh install of 2.2 just to see what the data structure looked like.
- We upgraded (1.9.17 to 2.2.3 - this was early June).
- We then modified the resultant data structure to match the fresh install. There are threads and tools you can find in Moodle.org's forums to help.
It all worked as planned. We've had some problems since then, but nothing related specifically to the upgrade, as far as I can tell. Whether you do the above depends on the geek support you can deliver or leverage, of course. Upgrading in place, then moving the resultant data elsewhere, is certainly possible.
I'll attempt to answer some of your specific questions...
- If you're going to try to maintain student work in courses, you have to have your users already in the database in the exact same manner in which they existed in 2.2. Otherwise, the restored course archives will fail to connect students with their activities and the content therein.
- HTML files will make the trip just fine, is my guess.
- Meta-course definitions depend on references to existing course #s - if you're restoring from archives, your "enrollment methods" will be retained, but the specific meta-connections will be lost. Shouldn't take long to restore. See above about any student content in them.
And, of course, none of the above problems will happen if you simply upgrade.
Again, my advice is an upgrade, and data structure audit to deal with the wretched excesses of your long upgrade chain.
Good luck!