My old high school classmate reached out to me after so many years asking how I am and wants to be friends. We never had a conversation, any kind of friendship in high school. It didn't matter to her then, so why does it matter now?
Some people get nostalgic when thinking about their high school experiences and reach out to "connect." I have several high school buddies that reached out to me on Facebook. What's wrong with that?
Absolutely. You have a common past and the mature people you are today is a far cry from whom you were in high school. Plus, none of us have too many friends.
It depends: Are you over the age of 18? If you are, how about you behave like an adult and actually learn to make your own decisions about things like this instead of asking for the unqualified opinions of utter, random strangers on the internet?