Premiere CS6 audio

OK - real dummy questions here - switching over to PrP6 and having couple of audio challenges can't answer.

1. we shoot split track XDCam. Track one usually ambient, track 2 lav. However frequently shoot both tracks with the one lav and have auto on track 1 and manual on track two - an old run and gun habit. The question - how do I get rid of a track. In FCP7 I'd unlink, delete one of the tracks, and the one I keep change to mono.
2. When I Overwrite or do an Insert, only the video drops to the timeline - no audio. If I a drag to the timeline video goes to V1 and audio is going to A3.

MacPro Intel 8 core 12 gigs, 12TB internal
unfortunately it seems an ATI Radeon 5870 card.
older MacBook Pro Intel Core 2 4gigs, NVIDIA cards but no Mercury hardware help.

Thanks guys - will get it eventually. By the way seems very fast and will play anything - format - that I've thrown at it.