I did a similar project recently where I had to keep Windows file server sync'ed with an FTP server in the DMZ for about 2 months while people were being migrated off the Windows server. I did it a little differently but the results worked.
I used a 3rd Linux box that was inside the network to mount the Windows server via CIFS, then used lftp to sync the files from the Windows server to the DMZ ftp server with command:
mount -t cifs //Windows_server/sharename/userfolder /mnt/ftpsync
`lftp -c 'open -e "mirror -R --delete-first . ." ftp://username
And then I iterated for each user. The benefit here is the file permissions get set correctly.
You could do something different, but if you don't know the username+password for each user, simply bulk copy all the data using scp or ftp or whatever, then run a script to chown -R the permissions to each subfolder.
The other thing you could do if you wanted to run this from the Windows box (i assume that what you mean by ntfs server), is to script winscp to scp the files over, then use plink to script changing the file/folder perms.
I don't think your step 1 will work, because ftp won't be allowed to follow a link outside of the chroot'ed base folder. (chroot - i assume that's what you mean by locking the users to their home folder)
Your step 2) I don't know about. I have never used the "--bind" for mounting anything.