A couple are quite tough to answer, but I'll give it a shot.
1) Everything that is wrong with the world - I've been thinking about this one and it's tough. I've had various things to say, such as 'everyone's beliefs should be accommodated', and yet I can't say that because some people's beliefs mean that they feel they can kill others. I feel that people have lost the sense of what is right and what is wrong. It's never okay to harm or segregate other people. If everybody remembered that we are all human beings before thinking about everything that distinguishes human beings from one another, the world would be a better place.
Everything that is right with the world - In spite of everything that goes off in the world, you still see and hear about outstanding kindness, caring and goodness that restore your faith in humanity. This can range from seeing a doctor save somebody's life or helping someone in general day-to-day life. There are still plenty of examples of decent people in the world despite everything that's going on around them, and those examples give you hope. I'm also going to take this question literally and say that nature is what's right with the world - it's a very beautiful place.
2) The most important lesson in life that I've learned so far is that actions have consequences. Something you do in a moment of madness can have wide-reaching long-term effects. You should think things through before acting.
3) If I could only play one game for the rest of my life... God this is a tough one because I love so many different games! If I absolutely had to choose, it would probably be The Last of Us. It's compelling and fun and the online multiplayer is very entertaining to me.
Wow. These questions really made me think!