Family Tree Help?

[Neo]

I am making a family tree, and I have some questions.

1. My uncle has never been married. The person he married has. Does this make his spouse my step aunt or aunt, seeing as my uncle has been married for the first time. (I also have an aunt who married her first time to someone who has been divorced)?

2. Referring to the question above, should I put their daughters on (Who had been born before the divorce-then-marry-again sequence) ?What are they to me and is it worth putting them (And the other two from above) on my family tree as they have no kin to me?

3. Are there any really good websites that can help me look up the relations of people whom I don't know anything but their first and last names? (I can handle those long lists of people with the same name, I just want something that will actually work!)

4. My cousin's cousins (And so on) have bo relation to me, I know that much. But should I put them on (because they are family of family)?

Thank you for your time!
I'm sorry for that confusion! I mean by "He has never been married" that he has never been married before. This is his first time, my aunt's second time. I just wanted to know if she'd be my aunt or something fancy.
In #4 I put bo. I mean know! (That mistake was stupid in so many ways...)