I'll second the warning on the westinghouse TVs. They really are crapily put together. For that large of an investment I would definitly reccommend spending the extra $200 or so and going with a comperable Samsung model would be definitly worthwhile.
As for installing, you'll want a wall mount bracket (you can find them locally or use http://www.mountsandmore.com then if you realy want to get fancy, get long video cables, run them through the wall to your suround sound equipment and cable box, or compuer equipment too if you want to tie that in. Good source of cheap long video cables is NWCA.com.
If possible, run HDMI video cables and Toslink fiberoptic audio cables for best quality.