For the rain effect that transforms the canopy windows in opaque blue stuff, you have to tranfer into FSX some files from FS9. Look into the main "Texture" folder and tranfer all the files that begin with "VC....".
The original problem is that FSX does not include the VC rain effect that FS9 had, so you have to take the textures of this effect from FS9 to FSX.

If you do not have FS9, you can look on the internet for the files rlvcrain.zip and also the Flight One VC rain fix. Both files are mandatory, because rlvcrain contains only the textures when the plane moves, but not when the plane is stopped. The flight one patch (on their website) contain the files for the stopped aircraft

For the prop disks etc... I do not have this problem. But I am using the FS9 default planes that are uploaded here at simviation, in the FSX Vintage section around page 14 if I remember well I do not have any texture or gauge issues (appart from the prop appearing behind the clouds and autogen, of course, but no transparency issues at all).

Most of the FS9 default planes are MUST-HAVE in FSX, I love them so much. I have installed the Comet, Vega, Jenny (new native FSX SP2 version, with self shadowing), Vimy, Trimotor, and the C182 of course. 

Indeed!
Those FS9 vc textures fixed the vc raindrops in stock vintage FS9 aircraft in FSX SP2, many thanks again... I was missing that vc effect in the windshield.