However, no matter what the version, you'll want to configure a user on the SQL Server that you will use to connect from the remote clients. Disable the 'sa' account and add some other account that is the sysadmin for the server.
You'll also want to append "Encrypt=True;" to the end of your connection string to make sure the data is encrypted to and from SQL Server.
TCP communication will already be turned on for anything above the Express edition. So, the only thing you'll need to expose the server to the Internet is some way to expose the port. If the server has a public IP address, then you just need to open tcp ports 1433 and 1434. If the server has a private IP address, then you'll need to forward tcp ports 1433 and 1434 back to the private ip address of the server.
I wouldn't call it stuck
Enterprise ConnectionPUBLICIPADDRESS
Express EditionPUBLICIPADDRESS\SQLEXPRESS