Okay. Captain Marvel is the poster child for OIHID. He CAN be built with Multiform, but OIDHID is the normal way to go about it. I do NOT agree that the change HAS to be mental for a multiform, lots of characters who can change into an animal will use multiform (say Changling/Beast boy for instance, though that is really a limited VPP)
Not the torch. I would say you are looking at (in 4th edition terms) an EC with Flight, Force Field, and Damage Shield, while having a MP of different "Tricks". Believe it or not 5th and 6th has actually made this simpler in some ways (thought long winded at times)
I CANNOT stress this enough, the main thing to do is KEEP IT SIMPLE. Many times you can get to the same destination in hero in multiple ways. Find the way that "feels" right to YOU...