Hey, thanks for all the help, and thanks for the command lines, Rascas.
When I ran sudo apt-get update && sudo apt-get dist-upgrade -y I got the same "failed to fetch" errors as when I tried to install kodi. Tried 20 times or so. It would get about 3/4 way through and start doing that.
It just felt like a species of a "timeout" error to me. So, just to see, I took the pi downstairs and directly connected it to the modem. It went through both installs fine. So it's something to do with the wifi.
Anyway, got kodi up and running - fantastic. Thanks!
Now I have a weird problem where kodi cycles through launch over and over with the PS3 controller in - it goes from the black screen with the grey config box to the kodi background (the blue bubbles) and then bakc again, flashing errors at the bottom of the config screen so fast I can't read them. If I unplug the controller, Kodi starts without any issues. Once it's launched, it works with the controller fine, but won't exit, reboot, power down, or anything else unless I unplug the PS3 controller. It just cycles through the same thing as the launch over and over with errors at the bottom of the screen, like I am restarting it. The minute I unplug the controller everything works perfectly again.
Works great with the keyboard, though. So my workaround for now is launch Kodi with the controller, wait for the Kodi bubble background, then unplug the controller. Then plug the controller in and unplug the controller to exit.