Not sure I 100% understand. “First View” has all of the normal browser caches enabled but they are completely clear before each run so disabling it doesn’t really make any sense.
As far as clearing a cache mid-script, that’s a lot trickier because we can clear the disk cache but a lot of browsers also have an in-memory cache which may or may not get cleared (there is a clearCache script command that should work on Chrome and IE but your mileage may vary).
If you really need a clear cache as well as authentication, the best way is to record a session cookie from your local browser and use the setCookie command to populate the test with the same session. As a bonus it’s also safer because you can log out on your desktop and the cookie becomes invalid.