"Question 2(a):
Explain, with clear justification and evidence, why IP has become the de facto protocol for packet based multimedia networks."

It hasn't. I could point out some ATM video conference networks that do quite well. But here's the reason TCPIP did so well... It's not proprietary. For example, NOVELL had a proprietary but good protocol, but it was closed.

There are history books about this. Why not go to a book store and read/buy an O'Reilly book on networking?

bob