Equipment/setup recommendations (1 camcorder, 1 mic) What are some of the best options for setting up an indoor, stationary scene?
The project is an instructional video with one human subject speaking. The final end product will be interspersed with screen-capture video from a laptop. Intended viewing format for the end-user will be streaming through the web, if that makes any difference.

From what I know, most "professional" camcorders can take both mic level and line level inputs. So I have a few questions:


Camcorder: Aside from video-related differences, how do video DSLRs or otherwise consumer-grade camcorders compare to professional (big 3-CCD) camcorders in terms of working with external mics? What considerations should be taken regarding mic level vs. line level, if any?
Microphone: Any recommendations for microphones at various budgets (~$50-300)? Would a lav/lapel mic or a shotgun mic be better? Background noise reduction is key (firetrucks, sirens, etc. creeping through closed windows).
Mixer: Would a mixer be appropriate here, considering the answers to the previous questions?


From my preliminary research, I figured I have a few initial options:


Buy shotgun mic and plug into camcorder (phantom power provided by battery/outlet, I assume?)
Buy wired lapel mic, plug into mixer/whatever to raise to line level, and plug into camcorder line-in
Buy wired lapel mic and plug into camcorder mic-in
Buy wired lapel mic, plug into mixer/audio interface to raise to line level, and plug into computer (and sync during editing)
Buy wireless USB lapel mic and plug into computer (and sync during editing)


I feel that option 2 is probably the best way to do it in terms of sound quality, convenience, and budget. Option 5 might be suitable as well if mixers are the bottleneck that breaks the budget.

Any thoughts or equipment recommendations appreciated. Thanks in advance!
Image quality and audio quality are really two separate beasts, so address each solution independently.  


  Camcorder: Aside from video-related differences, how do video DSLRs or otherwise consumer-grade camcorders compare to professional (big 3-CCD) camcorders in terms of working with external mics?
  Blockquote


"Big CCD" cameras are great at avoiding rolling shutter in the video signal, but this has no bearing whatsoever on the audio they record.  Since your question specifically addresses a stationary scene, though, rolling shutter shouldn't be a problem.  Another big advantage of professional video cameras is their connectivity to broadcast equipment.  But if you're not working in a broadcast environment, these features add unnecessary cost.  

With respect to audio, most dslrs and consumer camcorders ship with some sort of automatic gain compensation (AGC) enabled.  This reduces peak volumes and amplifies silences in an attempt to balance the volume.  In uncontrolled situations, AGC can be helpful, and keep your signal from clipping.  In controlled situations such as interviews, however, AGC will introduce unwanted hiss into the silences.  Make sure the camera you choose allows you to disable AGC for these situations.

Of course, the danger of disabling AGC is that your signal might clip.  To avoid this, consider audio bracketing.  Split the signal from your mic, feed it to a preamp on two channels, and reduce the volume on one of the channels.  That way, if your primary signal clips, you'll have a backup.  Feed both of these channels into your camcorder to avoid sync issues.  

Apologies if this doesn't make sense.  I'm not an audio guy.

In response to your question about lavs vs shotgun mics, I think this is a matter of preference.  Lavs are easy to set up, but they are more conspicuous than shotgun mics.  With a shotgun, you need a dedicated sound man, or a very stationary subject. Keep in mind that you aren't limited to "wired" lavs.  Wireless ones are actually the status quo.