Can you have lively/spirited/contentious conversations with friends without harming the friendship? How often?

With sincere friends, yes. And as often as time will allow us.

depends on who your friends are

Well, this is  a timed question.  I have a coworker who forever and always has his face in everyone's business, making vacuously stupid comments and giving unwanted evaluations.  I called him on it the other day.  He has not spoken to me in two days.  This arrangement is acceptable, even preferable to me.