Are those user home directories really gone? I've experienced what I believe to be the same problem (i.e. Lion Server failed to migrate my services and screwed up OD in the process), but the home directories never disappeared. Of course, if you reconfigured OD from scratch, you may have created new home directories in the process.
No, the home directorys had been still there, all other problems are the same as yours.
So I have recreated the OD, and during this, the User-IDs had moved to another.
And this is the main problem. How do I reassign the Userdata from iCal and Mail to this "new" User?
For the home directorys this is a small chown...