The answer is Yes. Pupils will adapt to its size through outside lights. In this way, it protects one's eye. But the pupils are influenced by both sphincter pupillae and musculus dilator pupillae. The later is controlled by the sympathetic nerve. When people are exciting or meet someone he/she interested, their pupils dilate. That is sympathetic nerve's duty.
Yes, it is true. When you see someone that you like or something that you have an interest or something that is shocking to you, your pupils will dilate because of the eye nerve's reaction. What's more, when you see things far away and then change into seeing things near, your pupils will always dilate, too.
Yes, indeed. Sometimes we tend to look into the the eyes of our loved ones. And of course our eyes, actually, the pupils will appear to be bigger than usual when we look into their eyes. This is primarily because our pupil will adjust its size to different distance. When you look far away, your pupils will on the contrary become smaller. The theory is just like a camera. So, it is true and it is quite natural. If you wanna know detailed information, just look it up.