Understanding Open directory - HELP

Hi everybody,

i read a lot about Open directory, but i need to have answers of the following questions:

1.Implementing Open directory replace the use of Local accounts on the server , right?In this moment i have Mac mini server with accounts.If i want to switch to Open direcotry accounts what i have to do?Do i need to delete all accounts and leave onli the admin account and create others in Open direcotry?

2.Can Open directory replace the way of connecting my Mini server.For time being users connect to the server via VPN and i have File sharing and they connest to folders thru AFP/SMB.Disadvantages are that Bonjour is not supported thru VPN.I also want that connected users to have connection to the MySQL server.Can i implement that w/out VPN?