Hi Anthony,
Good to hear from you! I hope all is well on your end and it sounds like you're working on an exciting project.
As Drew indicated, at the Esri UC 2014, some key announcements were made regarding ArcGIS for Server licensing:
- At 10.3, ArcGIS for Server Standard will include Portal for ArcGIS;
- At 10.3, ArcGIS for Server users will get additional named users depending on their edition (Workgroup vs Enterprise) and level (Standard vs. Advanced). See the link in Drew's post for details.
These are extra named users in addition to the named users that you get with the ArcGIS for Desktop entitlement (e.g., you get a named user for every license of ArcGIS for Desktop).
As a general rule of thumb, Portal for ArcGIS items (e.g., web map, apps, web services, etc) that are shared with "everyone" can be accessed without a named user account. In your case, it sounds like you will be using enterprise logins for authentication, which means that any member of your Windows Active Directory or LDAP should be able to access and use these public Portal items.
In the case of using the JavaScript application templates and the forthcoming Web AppBuilder (in Portal for ArcGIS 10.3), as long as the finished web apps are shared with "everyone", your end users will not need a named user account to access and work with them.
With regards to Collector for ArcGIS, yes - a named user is required to login to work with Portal for ArcGIS. As for the Esri Maps for SharePoint web part: someone who is authoring the web part in SharePoint will need to be a named user, but a named user is not needed to access the finished SharePoint page (that the web part resides on).
If you have additional questions, please send me an email to discuss further.
Hope this helps,