Membership and Licensing for Sharepoint Foundation 2010 single server installation with SQL Express Membership DB?

I have an OOTB externally facing site on a single-server farm SPFoundation 2010 server with SQL Express. It's not anonymously accessible, so I need to grant a few users admin access and a number of users Read access. 

1. Can I use ASP.NET Membership with SQL Express to create accounts for the SPFoundation site?
2. What are the licensing requirements? Are CALs required?