Is it possible to use a screw on polarizer filter and an anamorphic lens on the DVX100A? A matte box is, unfortunately , not in the budget at the moment.
It is mechanically possible, but optically it is not for several reasons.
First off, for the anamorphic adapter to work properly, its distance to the lens has to be matched to the characteristic of the adapter. If you add a filter (or any thing that adds space) it won't be correct.
Second, a polarizer needs to be able to rotate to get its effect. Since the adapter would be in front of the filter, you would end up with the adapter not square to the frame. This would result in a very strange effect to say the least. You can simply hold the adapter in your line of vision and rotate it to see what I am referring to.
A solution that you might want to consider is to use a large polarizer in front of the adapter (a 6" x 6" would be great, though a bit expensive) and just cut out a piece of black card stock to hold the polarizer in a "frame" and rotate it to get the correct angle for your shot, then just gaff tape it to the outside of the adapter. Its kinda of a crude fix, but it would work.