Most Helpful Girl
I wouldn't mention my ex while getting to know someone, but eventually the topic will come up. It shouldn't come up a lot though and you definitely have to watch out for this:
How often do you discuss your ex compared to your partner and his/her exes? I find the healthiest relationships I've had involved a mutual discussion of exes, often with inside ex jokes that apply to the exes of both partners. Like pointing at something rude and saying "Hey look, it's your ex!" and you both laugh. If one of the partners is friends with the ex, the ex should pop up in conversation no more than a regular friend.
Most Helpful Guy
Yes, but. . . not on a first or second date unless your new partner asks about your ex.
Yes, but. . . not excessively.
Yes, but. . . not frequently.