I am going to have a camera looking at an image on a wall driven by a
projector.  I want the camera to see the wall but filter out the
actual image from the projector.  My idea was to have a polarizing
filter in front of the projector and another polarizing filter on the
camera that will be looking at the image that will filter out only the
polarized light that the projector is outputting. (Seeing things that
may physically pass into the sight of the camera) My main questions
are:

Is this possible, and if so, what type of polarizers will i need?
(Circular, linear, etc) for each end (Projector and camera)

Am i completely off base in my idea, and if so is there something
similar in function (I'm no photography expert in regards to filters
and the like)

It's an odd idea so if anyone needs clarification feel free to ask and
thanks in advance!

you need two linear polarizers, one you can tape ar attach to the
projector lens and a rotatable polarizer for your camera. (SLR cameras
will be the best here). The projection screen will appear black when
the two polarizers are 90 degrees from each other, so you just need to
rotate the polarizer on the camera until the image disappears.

That makes sense to me, but then for a photo of the wall, you will
need additional unpolarized light, which raises the question of why
you can't just turn off the projector or block out the projected
image.