Actually you're basically an employee with a number of rights and responsibilities.
I'm a full time employee who is well accomplished, and even I still realize that there is a limit to how much influence I can exert over the business before I get the boot.
Approaching HR, or discussing the situation with your manager's manager in a 1 on 1 situation is a much better approach.
No! Never talk to HR unless there's a problem with your benefits or something. They are never on your side; they're basically there to protect the company from you. If you ever get into a situation you feel can't be resolved without involving HR, just start looking for a new job.