Yes it is true only in a few cases, this happens when comodo firewall pro is installed sometimes it does not turn off the windows firewall, in which case both the firewall continue to work...
Firewall define by its name only firewall means the wall of fire. firewall act as a security gateway between two network(usually between trusted and untrusted network) . Basically firewalls depends...
If you uninstalled Norton correctly, Norton 360 should no longer be there, check in the add/remove programs to make sure norton is gone, if so, contact the Norton customer service to remove norton...
If you have uninstalled your Norton product then you have removed it from the files and registry that would have it run so the firewall and any other items associated with that program should not be...