What would be an "acceptable" number of feature functions to have?
I'm asking because I'm not sure we will have time to put in thousands
or even hundreds of functions for the final project. We're currently
working with a small number of feature functions as we develop and
test our algorithms, but we expect to expand beyond those that we
currently have, although it might be difficult for us to get more than
50 or so. Another concern here is how well the project would work
without that many feature functions, and I guess I'll find that out
once we're able to start testing this.


I think for good performance you need at least a few hundred feature functions. However, I will be happy if you show that I am wrong!

This project is an educational experience, so if you do everything well except for some reason you have under 100 feature functions, you will still get a very good score. In your report, do explain briefly why you have not many feature functions, and what the bottleneck(s) is/are preventing you from having more.

If you do have 100s or 1000s of feature functions, then experiments using different subsets of these will be very interesting.