It means they like eachother. I don't see any other meaning of it. If you're comfortable with it, then I don't see a large problem.
You would flirt with your cousin just the way you would flirt with anyone else.
It means he is a flirt. Be careful of him.
If your friend is your cousin's cousin's cousin, that make the two of you friend who might, or might not, be distantly related.
No, don't flirt with your step-cousin.
It means she is flirting a lot with you as well.
it might mean he likes you but if he does not flirt with you then he is probably just adoring how good of a friend you are.
Your cousin would flirt with your crush because: 1. your cousin likes your crush 2. your cousin really doesn't like you 3.he/she doesn't know that that's your crush 4. your cousin wants revenge 5.or another one but I don't feel it's right for me to say it
B
That means he likes you possibly. My guy friend flirted with me sometimes in 5th grade, I flirted back.
Flirt with them the way your flirting with and opposite sex
This is a tricky situation but the best thing to do is not stress about it. Just because he/she is your other friend's cousin does not mean you have be friends. Just act casual and treat him/her the way you would want him/her to treat you.
It shouldn't really mean anything, unless it was dirty dancing.