Notwithstanding my username, I am actually a computer forensics expert. I can tell you first hand that he is doing something illegal, or at the very least, something that he does not want logged in any governmental database. Here are the red flags: 1. Cameras outside the house. This is sketchier than cameras in the house, from my standpoint. It means he is worried about a raid on your property. The cameras arent to identify thieves, they are to give him enough warning so he can wipe whatever drives he can before the FBI gets inside. Hence the motion detectors. I also have a feeling (correct me if im wrong) that he is using all SSDs. SSDs have a single line command that can be sent to them which instantaneously wipes all data. Excellent for quick response if someone were to raid him.
Cameras inside the house. These are for the purpose of seeing if any government agents come inside your house while you guys are gone, and planting keylogging software on his machines, or audio recording devices. They have a device that you place in a room and it records the sounds of keystrokes, and then can tell you what keys were pressed. This would give away the encryption key on a drive. See this link for a proof of concept. He wants to be sure no one has come into the home and planted anything.
VPN at the exit level. Your laptop isnt connected to the VPN, his entire NETWORK is routed through the VPN. This is super, super paranoid. Lets say his laptop is using the VPN at the laptop level. If he were to download a malicious program (or whatever), and executes it, that program could still "call home", giving away his actual outside IP address in the process. If ALL traffic on the network is tunneled through the VPN, it makes the likelihood that this will happen go down drastically.
I am 100% sure he is monitoring all packets sent on his network. Just in case the stuff I wrote about in my third point fails, then he wants to see exactly where the packets are going and coming from, so he can get some advance warning if something was coming.
I am shocked that he does not have an encrypted computer though. You were just able to turn his computer on and use it? This smells fishy to me.
That side, my conclusion would be that he is running some sort of hidden service for profit. Possibly one that deals with illegal drugs. Since the silk road went down, a few other marketplaces have sprung up (from what I have heard). He may be involved in one of those.
He could also be running some sort of bitcoin exchange. This would not be illegal. There have been many recent hacks on exchanges where they have lost millions of dollars in bitcoins. Hence the need for paranoid network security.
OP, I would suggest moving out. He is clearly concerned with a raid on his home, for whatever reason. Unless you want to wake up to the FBI breaking down your door, I highly recommend you GTFO.