More than 3 absences will lead to a reduction in your grade and may lead to your dismissal from class with a failing grade. Likewise, I plan to start class on time and expect that you will be there. Occasionally, you may find it necessary to be late. In that case, I would certainly prefer that you come after class has started rather than miss the entire class. However, tardiness should never develop into a pattern.
Any true discussion involves personal exposure and thus the taking of risks.
Your ideas may not jibe with your neighbors'. Yet as long as your points are honest and supportable, they need to be respected by all of us in the classroom. Encouragement, questions, discussion, and laughter are a part of this class, but scoffing is never allowable, just as disruptive behavior is grounds for dismissal. Moreover, once you get to class you are expected to stay in the classroom until the class is over. Leaving class early or getting up in the middle of class is considered disruptive behavior and should happen only in extreme emergenicies.