Pandora box of questions

I've been thrown into a moral conundrum regarding a job. Coincidently, I sat through an hour long lecture today, talking about ethics in competition for our MUN team. Here are some questions swirling around my little head. Any answers?

Is something unethical simply because you don't feel comfortable doing it?

What if a figure in AUTHORITY says it's ok?

Is legality the only standard of professional conduct?

My professor talked about being ethical to build credibility.
Does such a utilitarian view of ethical behavior somehow take away from the ideals of ethics?

Does your motivation matter, as long as you're ethical?