For a site collection, i enabled windows auth and FBA. For external users i need to disable the windows authentication to prevent internet attack of AD Account. For internal users both should be enabled. Is is possible to acheive?
Yes, just extend the web application (Central Admin). That will give you a second url, and you can configure the authentication settings for each separately. So now internal users will go to one url, and external users will go to a different url.
Thank You. Is it possible to hide the Role management in site settings?
Not at the moment, without modifying the source code.