Incoming Traffic inquiry

Hi,

we are setting up an application for external users (public) to be able to access it. It is a training module for the community so it should be available to everyone. I have couple of questions:

1) How could we secure our hosting server? yet keep people able to access the links?

2) Would sophos handle this large incomming connections? we might have 1000+ users trying to access it? What settings I should check

3) The videos might be of high quality? how to insure we dont disrupt our network and also end user side experience.

Any information can be helpful.

Thanks.

Reem