As Clinton stated, 16 channels will more than likely not be enough channels. It *may* be enough for smaller bands, but then you have to take into account an extra channel for your timecode, and and extra 2 channels for stage *ambient* mics, plus you will need a timecode generator to feed signal to your cameras, slate, and your rig. Also, be wary of computer based rigs on remote gigs of importance (which this certainly looks like) when running multitrack. Have had even my mac setup crash/choke on gigs. I immediately listed the interface for sale. Look into a deadicated hard disk recorder. Something along the lines of an alesis hd24 (if your running pre's/ad's in front) or and hd24xr if your going line in. You also want to look into reduncancy if this of the utmost importance. IMO, 24 channels will be the bare minimum you need to have available. Nothing worse than having to drop lines because you are short channels. I had this happen once (luckily not a paying gig) and it sucked. Never again.
If you are doing the video, why not outsource the audio to someone who will get you the product you desire the first time around? For example, we primarily provide audio for video. We are the subcontract help. This lets the video crew focus on what they are doing, and not having to worry about audio.
Another place to research where you will gain valuable knowledge on this subject is the remote recording forum on gearslutz.com.
Good luck!
-Jon