Are the contents of your van insured against break-ins (during the day when you're at work) or due to traffic accidents (or parking lot accidents)?
Unfortunately no. Just straight liability insurance.
Why not just save yourself the trouble of having to convert a van to be your home, and get yourself a motorhome? People might not think that as strange. And it comes with its own bathroom and kitchen.
First reason is that it isn't stealthy. You can't park a motorhome in nearly as many places as you can park a van. A motorhome just screams "Someone lives in here!" while a van doesn't.
Second reason is cost. Over the last few years I've put about 3k into this van including the cost of the van itself. Everything is new, built the way I want it, and I know the ins and outs of every system in the van. For 3k, a motorhome will be either one hell of a deal or at least 25 years old. Most motorhomes and trailers are incredibly poorly constructed and the recurring costs of repairs can spiral out of control.
How long did it take you to convert the van for your devious uses?
About a week and a half to get it livable before I actually moved in, and all the rest of the work has been done on the road. Here's a few pics of it as I was building it:
Used full size van + mats = 10k to 15k TOPS.
Used Motorhome is gonna be into the 30 to 40k range for something that is not completely falling down and worn out.
Not to mention the costs of fueling and parking a van vs. a motorhome.
I get about 12 mpg on the freeway, 10 city.
Does it weigh a lot and then like to lean over in the corners? Going up hills?
If you can build stuff better than Richard Hammond: 
Turning is a fun experience. Occasionally I'll take a turn too fast and the drawers under the microwave will open or if the fridge is full of soda, it will open and spill everything into the hallway
