Yes, you can be good friends after a relationship has ended. That person in your new relationship must be very understanding or problems will develop. Often, you must make a decision to break off a relationship with a person of the opposite sex in order to maintain a primary relationship with someone else. Yes, age differences certainly do affect relationships, but the larger issue is whether or not your expectations for your life and of each other match. A divorce definitely affects subsequent relationships.
Most people tend to be much more careful.
If you are dating someone who has recently been divorced, it's a very good idea to wait at least two years. Healing takes time. It usually doesn't work. Although you did not ask me directly what I thought you should do, I think you should recognize that your relationship with this man was a good experience for you, but that it was a short-term experience. Now, it is time for you to identify what you want out of a relationship, and then meet as many people as possible.