How do I limit the choices in a SQL Server column

In SQL Server management studio, I have a table called, Common.
Common has a column called, FLSA.
The FLSA column can only have one of two values entered:
1. Exempt
2. Non-Exempt
If I use a Check Constraint, then it will be more difficult for my Asp.Net web application's Entity Framework to pull the choices when I want to populate a drop down list in the HTML.
If I use a reference table called FLSA, do I add those two values directly and then create a relationship between the Common table and the FLSA table; OR do I use a check constraint on the FLSA table?
If I add the two values directly to the FLSA table, do I need a separate primary key field like Flsa_Id OR can I just make the FLSA column itself the primary key?
If I make the FLSA column of the FLSA table the primary key, how do I prevent any application from adding more values. There should only be those two values unless I manually change it through SSMS.