SmokinJoe, congratulations on your bravery, and your answers are in the right direction generally.
1) Yes. The increase in directivity would begin one octave higher--thus it wouldn't have nearly as strong an audible effect since the higher up you go above the midrange, the less sound energy there is to pick up, generally speaking.
2) With all large-diaphragm capsules there is a narrowing of the pattern at high frequencies, but the reason I specifically said "dual-diaphragm" and "cardioid" was because at low frequencies, that type of microphone loses directivity--the pattern broadens out toward "wide cardioid." So the line in the graph would dip down toward the bottom and rise at the top.
By the way, that's probably how the rumor got started that large-diaphragm microphones have better bass response: because most large-diaphragm microphones use dual-diaphragm construction (for example AKG, Neumann and their countless imitators). Since the microphone no longer has much directivity at low frequencies, it's less discriminating in what it picks up from the room "down there."
3) I'm with you there completely.
--best regards
P.S.: The high-frequency response of an omni mike doesn't decrease as you get further from the source, but in a normal music performance environment, high frequencies are absorbed more than lower frequencies as the sound bounces off various room surfaces, furniture, and people. As a result, the farther back your mikes are, and the more sensitive they are to sound arriving from all directions, the more likely it is that the sound energy itself will have a high-frequency rolloff on average. If the mikes are well beyond the "reverberation radius" then much of the sound energy they pick up will be diffuse in character and will have undergone numerous "bounces" along the way--generally losing some of its high frequency energy each time.
So that's why omni microphones for very distant pickup have elevated response on axis and basically flat response off-axis, but don't sound as if they have a peaky treble if they're really being used at a suitable distance in a suitable recording environment.
