1. I think you're just anxious and unfamiliar with sleeping with another person. This will pass.
2. Well, like nisses said, it seems like everything turned out okay, but you should be cautious about this in the future. Especially if you don't know the girl very well.
3. I don't have a penis, so I can't really help you with this one.
4. I keep from telling people about good sex I've had all the time. Again, maybe this is a guy thing...
Overall, I'd say you're just nervous and over-thinking things a bit. But, it's natural. It will pass as you become more comfortable with sex.