I think as suggested, the main thing to try is verify that once you plug the van into your house 110v, you should be able to plug in a lamp or something inside one of the van's 110v's and get power. Also verify that no GFI's are tripped inside the van if you have them. The fact that your interior 12v lights are not working at all sounds like either the main circuit is tripped, one of the 12v fuses are dead, or your house battery is dead.
I believe you should still be able to power 110v lamps inside the van (when plugged in) with a dead house battery as long as no breakers are tripped.
On a side note, for anyone interested, I recently bought a simple conntex adapter for use when my van is in the garage so I don't have to pull out the power cable at home. I use a regular extension cord to keep the van on house power and a small space heater with a freeze plug that kicks on when the van its 32 degrees. Can't have all that beer freezing in the van now can we?!?
http://www.amazon.com/gp/product/B002YB ... UTF8&psc=1