nlabs

Say you build a web app that cannot exist commercially without paying users (not a facebook). Yet you want to upwind the competition (to use pg's analogy) by being benevolent and offering free features - making it easy for users to get up and running with your software. The question is, when do you draw the line - when does a feature become "for paying customers only"? For example, how did Dropbox decide 2GB would be free - why not 10GB, why not 100 MB?

I plan on hiring a programmer or two on a part time basis. These will be undergraduates in Computer Science. What kinds of questions would you ask to determine a programmers competence during an interview?

Edit: Im looking for Javascript and python programmers