SC - Yeah, these two are wireless foundation. I have quite a few that are foundationless. I've had best luck getting my bees to build consistent foundationless drone comb in empty frames in the letter portion of the year. I used foundation when I needed to build drone comb early in the year, otherwise I end up with part worker comb, part drone comb, and that's just no good at all. Yeah, many frames end up with a chewed out are at the bottom. Most times this seems to get filled at least partially in the late fall with drone comb, or if not, sometimes the following year...but not always. Some colonies just seem to like to have that communication space. It realy seems to me that in my boxes that I have all the beespace dimensions just right, I end up seening these empty spaces. In the ones that have too large a gap between boxes, I get burr comb between the boxes, but the bottoms of the combs don't get chewed away. Too small of a space below the top bars and bottom bars, and they'll defintely chew them away for communication/travel space. At least that's what I seem to see.
MSW - Heading to the freezer means that I've removed this drone comb in hopes of taking a healthy portion of my mite load with it for that colony, and am sticking it in the freezer. Sounds barbaric killing the drones but this is a good way to get rid of a lot of the mites, without chemical use, and while supers are on. I started doing this last year in a few colonies, and now do it in all my double-deeps and bigger colonies, and I see very few mites, and no crinkled wings anymore. The frames that you're seeing are all drone cells, mostly capped (mites trapped), with the more consistent frame being (I beleive) from May 30th, and the second spottier one from August 14th.
Hope this helps with the questions, please ask if you have more, or see (spoiler - shameless Michael Bush plug:) ) Michael Bush's website for info on drone comb useage.