Those are three good ones. The first one has always been a pretty big one for me, my whole life. If I had to say the three major belief changes for me personally since getting into all of this stuff, they'd be these:
1. Women love sex, want sex, and some times, don't care if you don't call them or date them afterward. This was huge for me early on, both reading about it and then experiencing it.
2. Everybody has something interesting about them and it's my job to find out what it is, not their job to tell me. The day I adopted this belief the quality of my conversations and connections with women I met went absolutely through the roof.
3. People will behave the way you treat them. This is the most recent one for me, particularly in regards to really hot and/or young girls. I used to have all of these preconceived notions about them, so I'd treat them differently and then they'd behave to reflect how I treated them. Now, I just see them as other people and usually (not always), that's how they end up acting around me.
Even the dumbest and simplest people are incredibly complex and multi-faceted, and your expectations can bring out whichever facet of their personality you choose. Everyone does it and we do it to everyone else. If you don't expect a girl to be catty and dramatic and treat her in such a way that reflects that, then she usually won't behave that way.
This started to happen to me when I began to travel, and suddenly in some of these other countries, because I'm white or American, super hot girls would suddenly perceive me to be higher value (I still hate that term) and so I would see their normal human sides. I figured it was just a foreign thing, but then I came home to the US and my perception of girls like that didn't change, and amazingly, girls like that treat me the same way more or less, because I see them that way now...
I hope this is making sense... like I said, really hard to explain.
Check out these two stories. They each kind of get at what I'm talking about: