Are you allowed to sell infomation? Can you sell the coordinates of a Raw Material Deposit to a minning faction? Can you tell a bounty hunter the location of a wanted person for a little cash? Can you make an agreement give away the location of a fleet if you get paid?

Are you allowed or is it cheating?

You can "sell" information for "credits" see:
http://rules.swcombine.com/?Spying

In regards to other types of information it's all free game if you obtain it, and someone wants to pay for it.

Simple answer: Yes. For anything more complicated, read the rules.