High-quality guitar recording whilst also recording a video

Hey guys,
I've checked a bunch of sites and threads for this, but so far couldn't find exactly what I'm looking for.
I have a new MBP and want to record myself covering songs, with video from my built-in iSight and high-quality sound that is not just my guitar plugged in using a 1/4" to 1/8" converter, but a proper 1/8" analog to USB/Firewire interface.

First of all, how would I simultaneously record audio and video so that they are in sync, while still being able to edit my guitar sound (gain, EQ, noise gate, and other effects)
What sort of interface do you recommend? I know next to nothing about recording, so please go easy
Also, is it better for me to run my guitar through my noise gate (Boss NS-2) and distortion pedal first or simply use the features of my software?
Finally, what sort of software would I need? Is this doable with just GB and Photobooth?

Thanks