Sql-server – After I re-installed SSRS 2014 (with default config) I get HTTP 404 when I try to access the ReportServer or Reports pages

SSRS Planning a Deployment would be a good article to read through.

You can read specifically on the SSRS databases here. As it states:

A report server is a stateless server that uses the SQL Server Database Engine to store metadata and object definitions. A Reporting Services installation uses two databases to separate persistent data storage from temporary storage requirements. The databases are created together and bound by name. By default, the database names are reportserver and reportservertempdb, respectively.

You general, with large reporting requirements, will run SSRS databases on one server (shared SQL Server instance) and then the SSRS components on another. Keep in mind though how licensing works, you will have two licensed SQL Server servers with this type of setup. I normally see the report server databases reside on the same server as a data warehouse. I have not seen any issue with the SSRS databases being on a shared instance with the data warehouse. As it states in the article they are only storing information for SSRS (execution log, schedules, report definitions, etc.).

The "meat" of what SSRS does resides with the SSRS component services. SSRS processes the data the report is requesting and then also works out rendering it, all of this is resource intensive if there is a high load. It will depend on what your specific needs are if it justifies a standalone server. I generally will see SSRS installed on the web server with the application that uses the reports.

To determine if I need a standalone report server I would probably consider things like number of reports (many small or many large), the frequency (internal report server for monthly reporting or serving up user reports for external web application). You may also look at the report design or standard used by the developers, if the reports do a high amount of data processing on the report side, versus letting the database engine do it.

There is already an existing answer posted by Aaron Bertrand for SQL Server Express 2012.

First install SQL Server 2014 Express with Advanced Services as you did. Then read Aaron's instructions at:

https://stackoverflow.com/questions/10407337/express-with-advanced-services-cant-create-full-text-index

The short version is that the user interface does not behave properly when setting up full text. But you can enable and set up Full Text Indexing and Search through T-SQL code.