Yes it's wrong and you could be charged with "multiple submissions of the same material". Work done for each course must be created anew for that course. If you are wanting to expand on a previous paper, contact your instructor and discuss the best way to approach it.

This is tricky. You could be charged with "improper collaboration". Before working together check with the instructor and clarify the expectations for individual and group work assignments.

Absolutely. Ideas are considered to be the intellectual property of the author. You must acknowledge all sources of information and inspiration. If paraphrasing, be careful to use your own words, use quotation marks when taking direct material, and always cite appropriately. If in doubt, ask your instructor. Purchase a copy of "Using and Acknowledging Sources in Essays", available in the Bookstore for under $3.00.

Yes, you must give credit, regardless of the source of information. If you are unsure how to cite courses from the internet, speak to your professor.

It's not OK; it's called falsification of data or fabrication. What you should do is report your actual result and give explanations why you did not end up with the expected result.

Plagiarism is not a minor offence, it is stealing someone's ideas and passing them off as your own. And, yes, students have been charged and issued penalties on a wide range of academic dishonesty violations. These penalties range from a failure on an assignment to a course failure, a suspension or expulsion from the University.