They are unacceptable and may result in an F for the class. Never assume that I will. If I do accept a late paper, it will most likely be penalized. Keep copies of your paper on disk as you work on it, and until it is returned. Computer problems do not constitute a justification for late papers.
All papers are due at the beginning of class.
I expect you to attend class. Be aware you will get more out of the class, and will likely do better the more consistent and active your attendance. Participation can take multiple forms. Attendance and attentive listening are forms of participation. Asking questions, making observations, and responding to other students are forms of more active participation.