What are the choices for installing Reporting Services 2016?

The choices have not changed from previous versions.

During SQL Server 2016 Installation you can choose to specify Reporting Services Configuration mode.

There are two modes that you can specify Reporting Services Configuration:

Reporting Services Native Mode
Reporting Services SharePoint Integrated Mode

You can choose both modes or just one mode.

If you choose to install the Native mode there are two options:

Install and Configure
Install Only

Install and Configure option installs and configures the report server in Native Mode. However you need to do further configuration for your specific case. The Report Server is operaitonal with the Windows Service and the databases needed by Reporting Services in your named instance.

Install only installs the report server files. You need to use the RS Configuration Manager to compele configuration.

If you choose to install the SharePoint Integrated Mode you can only install the Report Server files but you will need SharePoint Central adminsitration to complete configuration.

Details for both modes of installation for SQL Server 2012 were described in my book:

ISBN 139781849689922

Paperback566 pages

How do you create a Report Model in SQL Server Reporting Services 2016 (Native Mode)?

You cannot as it is discontinued.

RS Web Portal is the new name for Report Manager of earlier versions.

The following two features related to Report Model are discontinued  in SQL Server 2016.

Feature                                                                Replacement or workaround
Upload report models through the web portal     This can still be done through the SOAP API.
Manage report models through the web portal    This can still be done through the SOAP API.

Note: Whereas HTML4 is supported, the future SQL Server Reporting Services will be using HTML5.