a) targets all the countries (so it is not limited to Europe or America but also Asia, Africa, Oceania)

b) forecasts to have thousands of members registered and hundreds of members connected at once

c) photos and other files

d) wants to have the lowest ping and the highest speed possible

e) is not managed by someone who knows how to handle a server

If you were in this position, what would be your choice?
Could you please help me finding a solution that will be able to do all what is written above? 
and which will be the prices?