@cglock: Answer to Q1 is no t right. Setting the Multires Prev to 2 does not achieve anything. In fact it's already at 2 in Kent's provided start.blend file.
This same problem is mentioned several times in the Q&A all of which have no answer or solution, still 3 years later. This has been my biggest and only gripe with CGC since I started 4 years ago.
Hey guys, you don't need worry about if you're having the alpha-less grey background on your Bake-DISP maps. Because you will ultimately be creating a mask for it in Photoshop anyway. Plus, as Kent has commented, "No alpha means smaller file size, which is good." Just go ahead and proceed with your grey map and you will be perfectly fine. Cheers, and happy Blending everyone! Hey Hardus Jonker, the answer to your 2nd Q is: Go to the options tab in TexPaint Mode and look for "Show Brush" and enable it. :)