Installing Norton Security - Best Practice

My current subscription to Norton Internet Security will run out in a few weeks and I have bought a Norton Security Card in order to download the latest protection.

(Q) Will the new product automatically uninstall my current Norton Internet Security for me ?  OR...

(Q) Is it a good idea for me to manually uninstall my current Norton Internet security before attempting the download ?

(Q) Would it be even better to use the Norton Removal Tool to strip everything out, or is an uninstall good enough ?

and finally a big question...

(Q) During the period between removing my current Norton Internet Security and completion of the installation of Norton Security,  my PC will be completelly unprotected for a period of time. Is this potentially dangerous ?

How should I proceed ?

Thank you.