Well, first things first, I wouldn't spoil them rotten. If they want to buy something they will not get pocket money, they will ask me and I will buy it for them if I feel they have earned it.
When it comes to age ratings, I wouldn't really care. Even at the age when they are just able to pick up a controller I will let them play almost any game they want to. At a very young age I might keep games like Grand Theft Auto off limits, I honestly believe that violent video games really don't have that much of an effect on children, it's all down to parenting and letting them understand it is just entertainment.
I will also let them game as much as they want if it's their hobby, but homework and real life issues come first. I will not let them play games until they get these things sorted.
Basically, I will raise my children in the same way I was raised. Playing games like Resident Evil and Metal Gear Solid were a great experience when I was a child, I had such a great imagination then and I found those games much more thrilling then than now. Playing these types of games didn't make me a violent person and if anything they helped me mature faster. I never had a "thirst" for violence either, it was the game I cared about, not the gore. I would always put down Resident Evil to play a bit of Sonic.