1. You don't need to notify QV Support, unless your are working with them on an open ticket. In which case, it would be beneficial for them to know. As long as your maintenance payments are up to date, you shouldn't need anything else.
2. The ports should not have changed, so if your existing ports are still open everything should work as designed.
4. QlikView Server Manual has a decent installation section that can be referenced. There are document when upgrading from previous versions, but nothing within version 11.2. The installation process is straight forward and will inherit your existing setting, but you should backup the setting folder, just in case.