How to keep browser open when in development and how to clear cache when closing it?

I'd like to know how I can prevent the browser from closing when the crawling is finished?

Also, I have a crawl that needs to sign in the user, however if the user is already signed is the site redirects the user. How can I clear the cache of the browser whenever he browser is closed? I'd expect the cache to be cleared each time but it doesn't seem to be the case.