With ATT DSL, you normally purchase the modem from ATT (check your contract). If you want to use a different modem/router, you would first need to be sure it's compatible with your service by checking with ATT (usually listed on their website). If you are not renting a modem from ATT, you will still be paying $41 for service, even with your own modem. Essentially, you are being charged for internet service, not for the modem itself.

Changing out your modem/router does not affect your browser or email settings.