There are three types of houses: the most basic is just a room that lets you save, replay missions and manage your drug stash; second has a room and a garage; third is bigger and is considered "secluded," so when you do steal a van and want to check the supplies, you need to go to one of these.
Outside of the houses you get for story purposes, I only got one other that I won by scratching tickets. I'm waiting until I have over 100,000 before I go out and buy a bunch of places to use. I just made about 50k+ when I started focusing on the drug trading, so I don't expect that to be so difficult.
Drug trading is really simple. The game tells you where the dealers who sell drugs cheap are and those who buy high; it's as simple as buying from A, selling to B and making a profit. I usually don't bother with that since it's slow, but you still get emails every once in a while with people telling you about people selling at low and buying at high prices. Sometimes it seems like spending 30 thousand on heroin isn't a good idea, wait a bit and find someone willing to pay much more than what you spent and make a huge profit.
I've found about five or six rampage missions so far. I don't know exactly how much I've played so far and I'll check if it says in the stats next time I play.
