Basic Set Theory Question

1. How many subsets are there of the set {1,2,3,...,n}? How many maps of this set into itself? How many maps of this set onto itself?

2. How many functions are there from a nonempty set, S, into the null set? How many functions are there from the null set into an arbitrary set, S?

To anyone helping me with the above two questions, thank you! I am studying analysis on my own, so any help is certainly appreciated! Those two questions came out of "Introduction to Analysis" by Rosenlicht.

Also, if you have any suggestions that might be more suitable for self study, I'd be very thankful. I don't have any solutions in the back of this text! Haha.