1) A nice, clean, direct sound can be had by the direct to turntable hookup. Just use the RCA plug adapter that came with the iMic and plug the RCA cable connected to the turntable into the adapter.
2) Make sure that you have Final Vinyl installed in your Applications folder.
If not, go to www.griffintechnology.com to get a copy for free. Once it is installed, start it up and click on the little Preview button. This will allow you to hear the music from your turntable without recording.
3) The left/right channel is a matter of trial and error. With Mac OS X, go to your System Preferences and choose Sound. Place the tone arm in the middle of a song, then, with one plug from the left channel of your turntable plugged in, slide the Balance control in the Sound Preferences to the left. If you don't hear anything, then connect the left channel to the other plug in the RCA adapter. Try again. You should hear the left channel when you slide the balance to the left. It is extremely important that you get your left and right correct because if you don't then the music will not be heard the way it is intended. If the left channel is one the right, then the music image and separation will be different so get it right!
4) There is an EQ feature in Final Vinyl that comes in VERY handy when recording records. The mix is usually optimal on recordings but the emphasis on certain frequencies MUST be changed to hear the music correctly. There is a button that compensates for turntable levels on the bottom left of the EG. If you can hear music, then DON'T use this; you will overload the inputs.
5) The one thing you need to do with the EQ is compensate for the relative lack of bass that is recorded into LP records. The bass is attenuated (turned down) severely when cutting the record to fit more music on the disc. You see, bass frequencies translate into visibly squiggly grooves on the record surface, so they are turned down making the groove much more fine, thereby taking up less space. You must compensate by clicking on the EQ preset Bass Boost or turning up the individual frequencies to your taste.
6) Beyond that, recording this way is pretty much self-explanatory. Go with what sounds good to you. You are going to be the one listening, right?