Okay, so I wanted to do some basic signal processing in Python and found this great library called scikits.audiolab.
scikits.audiolab
No PPA anywhere to be found. Oh wel
Edit: I just realized this is not the case as pysndfile seems to be bundled... I shouldn't be answering stuff the first thing in the morning ;)
Answer to 1: Sndfile is a c library, you most probably need to install the python wrapper for it: http://code.google.com/p/libsndfile-python/