Answer to: If I am willing is there a way?You would really have to pay attention to screw placement on the new board but it's perfectly feasible to do. Although you would most likely have to replace stuff besides the logic board in the swap because of the different specs and most likely the need for a newer gen charge port or higher wattage power requirement.
Answer to: Backlight not working, display does after changing hingesReset the P-Ram, if that doesn't work pm me.
Answer to: Running slow and the fan is loud.Start by trying to reset the P-Ram(cmd,opt,P, R). If this doesn't help boot it holding option and throw it into recovery mode, back up your files and reinstall os x. Should be a fix. If this doesn't work its the logic board itself.