Let me start with the part where I know the answer offhand. Later we'll update when we find more complete information.
1) Yes, all these substance absorb linearly-polarized light. Every linearly-polarized wave can be described as a sum of two equal-magnitude waves with opposite circular polarization. So even if you have a 100% circular dichroic (CD) absorber, it'll still absorb that part of the linearly polarized wave with one of the circular orientations. Of course what's left is no longer purely linearly polarized.
2) Yes, there are solid dichroic materials. Lots of crystals (especially ones of biological materials, but not just those) show optical rotatory dispersion (ORD) in the visible- they rotate plane waves. Sugar is an example. I think it was Pasteur who noticed that synthetic sugar crystals had ORD, some of one sign and some of the other. Now there's a deep mathematical relation (Kramers-Kronig) that says that ORD always must be accompanied by CD at some frequency. If we find some data on what solids have particularly high CD we'll update this,
Mike W.
(published on 02/20/2008)