Copy and paste "Find a serial number - Adobe" into your search engine and hit enter on your keyboard. Click on the "Find a serial number - Adobe" link in the search results, it will take you to an Adobe support page that will help you get your serial number.
No Photoshop CS5 and Photoshop Elements are separate programs.
CS5
yes.
Photoshop CS5
Photoshop CS5
Yes, you can upgrade from Photoshop CS3 (or earlier) to Photoshop CS5 Extended, no problem.
cs5 is better
In Extended version you have 3D Tools to work with 3D Objects.
Adobe Photoshop CS5
It is a unique string of letters and numbers that you have to input in order to install the progarm. You have to pay money for this.
Adobe photoshop CS5 (extended)
Yes, because the serial code is the heart of every program.