You can rely on a database size of 2GB. I don't know if it can yet be larger.
All of the languages you describe are procedural programming languages which allow you to spell out, step by step, exactly what the computer is to do. Basic and C++ are both general-purpose languages; FoxPro is more database-specific.
Are you looking for an application development environment that is easy to use and has good database connectivity ? Or are you concerned with performance ? How much data will be stored in the database ?