First, I would use a simple hand held casset tape recorder to record my sound.
However, I would attach through the Mic Port a small shotgun mic that i have (similar to one in pic)

I would probably just tape the mic to the top of the recorder and hand hold it, pointing it towards whatever I'm shooting at the moment.
Questions: Would recording to the tape mean crappy audio quality? (Maybe I could get one of those special high quality cassettes)
Would outputting the audio back through the player and into the computer through the line-in audio port cause any problems?
What Khz would I want to capture the audio on the computer at? 44khz? 48khz? maybe lower?
Lastly, how hard do you think this will be to sync up to the film, assuming I have an indicater such as a finger snapping, hand clapping or something like that?