Hi Autoboy,
The in-wall portion of the speaker was designed and built to fit between a standard 16" center to center wall. If the wall is not a bearing wall; a stud could be cut out without negative effects. If it is a bearing wall then someone can always built a header similar to what is commonly done for a window or door opening.
You should install the main speakers so that their tweeter is between the ear level of the first and second row of seated listeners.
With two rows of listeners; two center speakers are highly recommended. If only one is installed, it should be above the screen and aimed again between the two rows of listeners. An Axiom VP150v2 on a ceiling or wall bracket is easy to aim. However, if you want a W150 build a sheetrock box with an angled face which will aim the W150 between the two rows of listeners.
