I recently outfitted a few vans for my family business. The most important thing you can get is a partition behind your drivers seat (and passenger if you will have any). If your van doesn't have high backed bucket seats with headreast then get a headrest that mounts to the partition so your skull doesn't crack in a rear end accident. If you don't have partitions and you get into an accident then you might get a screwdriver through your melon. Even at 30 mph a flying hammer can ruin your whole day.
As for where to get all this stuff, I have bought a ton of stuff from American Van Equipment, 1985 Rutgers Univ. Blvd. Lakewood, NJ 08701 PH: 1-800-526-4743. They have a great catalogue you should get. I don't think they have a web site. A web site with a lot of the stuff they sell is http://www.adriansteel.com I think they mostly sell to outfits such as American Van and GM/Chevy b/c I see their stuff in AMVAN's catalogue. American Van has all the ladder stuff etc. that you need.
You also need to be concerned about how much weight you are putting in your van. Is it a 1500 (half ton)? If so, you should go down to your local spring shop and get helper springs or something. Also keep an eye on the integrity of your front end. Heavy loads take their toll and I have to rebuild the front ends on my one ton vans at about 100k miles. Good luck!