It's perfectly ok to use a quote from a text book in a presentation and/or homework, however, it is not okay, nor ethical, to use it without appropriately giving credit to the author.  Not appropriately citing the author, date, and publication the quote is plagiarism which is unethical.

Study groups are encouraged, however, it is important to remember that sharing information with each other is great, as long as sharing doesn't mean copying others work.  Copying other study parnters work is wrong and unethical. 

A healthy classroom environment is important to learners, however, sometimes a student will exhibit behaviors that challenge the quality of learning.  Each situation is different and should be addressed on a case by case basis.  Students with disabilities where and continue to be excluded in many instances.  It is unethical and in many cases illegal to discrimnate on the basis of a person's disablity, so ethically and legally it is important to adapt the environment so any student gets a fair chance at an equal education.   

It is unethical to cheat on your homework, tests, and any other educational assessment, however, many Colleges and Universities require anyone who knows of such cheating to report the offender.  

It depends because some instructors allow "open book/technology" tests.  And in those cases it is ethical to use what ever technology is allowed in the classroom environment.

The important point here is that teachers and students are both under ethical requirements of being honest with each other, communicating respectfully, and understanding the point of view point the other side.  

Competition to innovate can be great for human kind and it can also present it's own ethical issues.   The intense competativeness may result in ethical issues as personal and corporate privacy.  Think about all the data breaches of companies around the world.  Yes, the more pressure to innovate and beat the competition has increased the changes of further ethical issues and dilemmas.