1. Way to sum it up. > This means you've done a good job of summarizing the situation or facts. It is often said with sarcasm.
2. I'll keep him company. > This means that you will stay with him. "Keep someone company" is an expression used to say you will be a companion. Often it is said when others need to leave.
3. He is A great hang. > I've never used this one, but I think it means he is great to spend time with.
4. The wrong people get to be immortal. > Again, I have never used this but it means that the people who are remembered after death are generally not truly worthy of the distinction.
5. I blame that on the heat. > I'm really not sure about this one. Sorry. Maybe, because it is hot, he was hungrier than I realized and ate more than I expected. I'm guessing.
6. It's all in how you present yourself. > 'to present' can mean 'to show oneself to others or at a place.' So this one means that how you present yourself can make a big impact on how you are perceived. dictionary.com