It all depends on the kind of work your users are going to be doing and the size of the file they'll be working on.
If you already have a network/shared folder in your organisation, check there to get an idea of the typical file size.
Most of Nuxeo is generated html pages, so not that big in bandwidth requirement. And you can mesure it with a proxy or something similar. Other than html, size is going to be dependent on the file you transfer to and from Nuxeo.
Intranet vs Internet depends more on accessibility from outside the corporate network, either remote working or sharing with clients/partners.
Finally, do you have to have all the information before hand or can you install, test and update/adjust if necessary?
