It is possible... Just be aware that he (or she) might find someone else, and you might become jealous. I had a bf, and found it better if we didn't talk after we broke up. This was because he got another gf and it was annoying for me to always see them together when I talked to him. Anyway, do what will work for you
It is very possible. However, friendship with your ex will depend on whether or not both of you have feelings for each other. Once feelings are involved, both of you might end up getting back together.
Of course, just gotta know and understand that you two aren't together no more (meaning you should respect yourself, ALWAYS) and you can't get mad if like he's talking to some other chick and it may seems like he's ignoring you.