Need Suggestions For Upcoming PIC Project

I want to build something that allows me to record the output of an
electret microphone onto a USB memory stick.  Ideally, I'd like to be
able to record mono/stereo at various quality settings, say, voice audio
all the way to full music quality up to the limit of the mp3 format.

I am quite familiar with the analog end of this problem, and have done
a number of medium complexity PIC projects over the years.  But ... I
have a few questions:

1) Is there are PIC part that can do the A/D at the appropriate rates
    for the desired audio quality settings?  Is there a better part than
    a PIC for this?

2) Once I have the audio in memory as a bitstream, are there open source
    routines to create mp3 format files?

3) Is there a standard hardware/software library for interfacing with
    a USB memory stick and dealing with its file system.

Effectively, what I want is a small, low power replacement for a
cassette recorder.

TIA,