Google drastically lowers the rank of sites that aren't "mobile friendly" in searches on mobile devices. We've basically followed their specifications as closely as we could for what's mobile-friendly.

Its not mobile friendly. Its worse. I get 2 images in a row then have to keep scrolling down while my tags are constantly hidden.

Where is the option to change layout?

At the bottom of the page.

So... how many time must this be done before thumbnails return?
no cache, extensions disabled, fresh install of chrome and firefox. East US IP
after coming for the first time, thumbs will flash and then disappear.
only see ads, search-tagbar. Banner ads clip with tagbar

Sounds like you have an application modifying the website. I don't know what you tell you. Check to see that you don't have any third party tools messing around with the browser, such as Avast?

Is it intentional for deleted posts to not have red squares around them anymore on browser?

Does not happen every time, but I occasionally have the "nobody here but us chickens" message appear when I click on one of the tags in the tag list on the left side.

I also find the non-uniform distribution of thumbnails a bit disorienting.

I'm retarded and don't see it, even with all extensions disabled.

I have moved it to the top of the page.