I'm really confused now. Yet another wipe/re-ROM got Titanium talking to Google Drive (and I now think the problem was app stuff on the SD card, NOT the ROM, so I wasted a (bleep) of a lot of time and hassle rebuilding my phone more than once), and I ran into trouble re-installing apps from the web Play Store (downloads weren't happening). A reboot didn't help, but unplugging the charge cable did. What rational reason could there be for Play Store not downloading to a phone that's plugged in? 
Update: I'm now unable to download if the web site initiates it either way, and I can't get an app I bought to show up in my list of purchases so I can download from the mobile app.
Update: I'm now unable to download if the web site initiates it either way, and I can't get an app I bought to show up in my list of purchases so I can download from the mobile app.