In all this mic talk outside, be sure to have wind protection as well. Also to add if the zoom F4 or F8 are within your budget, they have adapters to attach to the camera, so you can feed your wireless lav and wired shotgun into the recorder, then output from the recorder to your camera, so you have the higher quality recorder audio, but also high quality feed into your camera (gives a little extra redundancy and makes sure the sync of external audio tracks will be super easy). Regarding over modulation, some of the external recorders can record onto other channels at lower levels so that gives you a little more protection.
For the physics just remember signal to noise ratio, you want the mic as close as possible to your desired source so that it will be MUCH louder than the background (non-desirable) source.
