Can anyone help me with how to record sound at a small gig?

Basically, I've never done it before, but I've been doing some reading up on it and I'm wondering whether I can do it with the limited gear I have and secondly, where to get the sound from.

I will have a handheld camcorder and the venue size is approx. 200 capacity. I might have access to the soundboard. Should I try and get sound from there, or would it be no good? I understand that I will need either an RCA, XLR or TRS adapter to plug into the board and direct to the camcorder or should I have another adapter? Don't get me wrong, I will contact the venue prior to the gig to ask If I can plug in and what adapter I can use to plug in.

Could I alternatively record the sound with an MP3 player using an external mic plugged in and then sync the sound up with the video in post? I have a Cowon J3, wondered if that would be any good?