There is a large thread at UBBDev about experiances with 1and1, additionally I believe there are sevearal at
www.webhostingtalk.com... They're very fickle, and I don't believe their MySQL will support your install (iirc they only allow 100mb mysql databases for starters, and their servers are quite anal).
As for upgrading, the interace between past products and UBB.T7 is totally differant, theres not much ability to change how it looks short of hacking templates; though a bit can be done with a style (I myself do styling work, as do others).
You'll need to upgrade your UBB.Classic to 6.7.3 then migrate over to UBB.Threads7, this is a requirement as the importer was created to work only within the 6.7 series and you will find issues trying to import prior versions.
I would also not recommend ever trying to edit the UBB files with FrontPage or FrontPage Extensions, you'll end up screwing up how data is stored and it'll basically destroy the files.
In the general forum there is a thread on upgrading from UBB.Classic 6.7 to UBB.Threads 7, it's pretty laid out on exactly what needs to happen.
Step one in your case would be copyng your old files to the new webspace and import; but keep in mind various 1and1.com issues this could end up halting all operations in the first place.
