The two primary reasons that it interests me is because recording on a device like a Zoom shows recording levels and also allows monitoring (I am pretty sure?). Neither of these options are available with the Canon T2i and other similar-range DSLR video setups as far as I know.
what actually happens in the field is that the audio guy has a (non-USB) mic going into a compact mixer, usually from Shure or SoundDevices. that mixer provides phantom, headphone monitoring, levels, meters, panning, etc.
The output of that mixer goes to camera so that audio and video are laid down together, in sync. typically that connection is wired, but often real pro's will do so wirelessly. (and they'll also have a compact recorder, as well, from SoundDevices, that's not only sync'ed to camera clock wirelessly, but will automatically go into/out-of record mode when the camera does).
for your purposes, i suggest you get a (non-USB) mic that either mounts on the camera, or is boomed and connected via an XLR cable. you would plug headphones directly into camera for monitoring, and when setting levels you can look at the camera's level meters. Much of what happens when shooting, though, is done via listening.
Booming is hard to do well, and even with a fairly static scene, one must keep the mic positioned on the current speaker, out of frame, on-axis, and in time to catch the start of the dialog every time actors deliver lines. that means you're actually moving a lot, which is why trying to do all this while recording to a laptop seems somewhat absurd to me.
doing all audio in post also seems absurd to me. heck, you're on location with all the sound happening as it's being shot, why not just capture it then and be done? or only dub the lines that you didn't get, instead of trying to have everyone lipsync everything later, and try to foley-in all the noises that one would expect to hear to match what they're seeing on camera?
