Your question is too open to give any specific hint. In my experience, even the most media rich Moodle sites consume less bandwidth as one would expect. Obviously that times the number of active users. You can easily calculate the traffic volume as the file size times number of downloads.
The traffic volume is often not a critical factor in deciding the location of a server, the latency http://compnetworking.about.com/od/speedtests/a/network_latency.htm
may be. It all depends how Oman is connected to the rest of the world. I have come across "network islands" where the overseas connection was always a bottle neck.
If you have lot of quizzes, the processing power of the server becomes an important factor. Go through the performance documentation (linked in the introduction to this forum) and past discussions in this forum to find out more.