If you haven't passed the bar and been admitted to the bar, you don't get to practice law. You could act as your own attorney, but being a law student doesn't make you any more qualified than say, me. Law firms do have clerks that work like during summers and get experience doing grunt work that way. If you think you have a case, hire an attorney and volunteer to help out and see what they say.
Yep. $200 to $350 per hour is a reasonable rate. (The rates for paralegal and/or legal secretary should also be disclosed and those rates will probably range from $50 to $125 per hour.)
If you are asking for a specific service (i.e. estate planning, etc.) you can ask for a fixed quote. You should also ask how much time you anticipate the attorney believes s/he will need to spend on the case. This will give you an idea of what you'll have to spend.
I'd recommend that you contact the Massachusetts Bar Association. Their website will probably have a referral service. And you'll be able to make certain the attorney you're interested in hiring is a member in good standing, etc.