A common misconception is that shotgun mics can "reach" farther - when in reality this is not true. Using a
shotgun mic for sound is like using a papertowel tube over a camera lense; it doesn't reach farther, but "spots" a certain area of sound and rejects sound coming from the sides and back.
To answer michael's question you don't have to have someone aiming the mic constantly, but it will affect your audio the same way someone stepping out of a spot would affect you lighting.
AG - remember, the more open mics you have in a room the less gain-before-feedback you will have. It doesn't mean you can't use all the mics you want, but you're going to want to have a few EQ's in your
house rack. I prefer 31 band eq's cause they give you a much higher detail control, but a 15 band would work as well. The best way to limit the number of eq's you'll need is to run a number of channels through sub-groups, but make sure all those channels are the same type of mic.
hope this helps