Using the mic preamp on your soundcard you will only be able to record one channel at a time...plus the quality will be poor. More common practice is to use external mic preamps or a the mic pre's on a mixer, and you run that into the line in port on your soundcard. Since the line in port is stereo, you can record two mono tracks at a time.
n-Track can record and playback any number of tracks, as long as you have the computer power. The number of tracks you can record SIMULTANEOUSLY, however, is limited to the number of inputs on your soundcard. There are high quality soundcards out there with anywhere from 2 to 8+ inputs and outputs.
Slackmaster 2000