Hi,
As a matter of fact, I've never used vsftp...
But,
For the 2nd question, there must be some kind of motd (message of the day) banner that you can configure in the vsftp config file
For the first one, I'll take an exemple with, say, a "shared_folder" shared through samba or nfs on the "my_machine" computer.
1/ create a /mnt/my_machine folder on your ftp enabled machine
2/ mount shared_folder on your ftp enabled machine, in /mnt/my_machine
3/ configure vsftp to allow users to download/upload files in /mnt/my_machine