2. Where on the HR diagram is it? What is its energy source?
The protostar will be warm and, due to its size, very luminous, thus placing it in the Red Giant region of the HR diagram. The temperature of the protostar increases due to gravitational contraction, and its luminosity decreases since the surface area gets smaller. The contraction stops once the the core reaches the temperature needed to fuse Hydrogen into Helium; the star will be on the Main Sequence at this point.