Deep Thoughts

Last night I was listening to talk radio. The host was speaking about about ethics and morals and "situational ethics" which got me wondering a few things. First of all, what's the difference between ethics and morals?

Ethic - a set of moral principles : a theory or system of moral values

Moral - a) of or relating to principles of right and wrong in behavior b) sanctioned by or operative on one's conscience or ethical judgment.

Morals rely on one's own perception of what is right and wrong and ethics are a system of moral values generally dictated by society (business ethics, medical ethics, political ethics, etc).
So, my questions are: Do ethics change from situation to situation? Or do your ethics stay the same no matter what?
Morally you're against killing people but you support the death penalty. Is that situational ethics?
Can you be for the death penalty but against abortion? Aren't both acts of taking another life? Or how about the death penalty and euthanasia? Can you be for one and against another?
Can you morally think that homosexuality is wrong but ethically be opposed to the legal discrimination of homosexuals?
Can you morally be opposed to birth control but ethically think that certain people be sterilized?
Is lying by omission to gain favor morally or ethically wrong? Can you lie in certain situations and justify it while morally being opposed to lying?
What do you think? Can ethics be situational? What about morals?