-Photographer
-Graphic Designer
-Web Designer
-Advertiser
To name a few.
you can use any photoshop but i tend to use CS3 or CS4
Most digital and graphics design artists use photoshop. Those who can't afford Photoshop usually use GIMP or Corel Paint Shop
When you show your products photos to your customers and need to edit them, you will use adobe photoshop.
Photoshop Elements is Photoshop but with less features, so Photoshop is better but it is professional level software. For home use or to get started Photoshop Elements is OK.
No, they are separate programs or software's to use and to buy.
Adobe Photoshop tutorials online has thousands of free tutorials to teach you how to use their photoshop. You can also use photoshop or adobe to find all the answers to your questions as well.
Photoshop have Horizontal Type Tool and Horizontal Type Mask Tool which you can use to type text in Photoshop.
No, Liquify requires Photoshop to work. Much of the code for Liquify is actually in the Photoshop application not the plugin.
No, Photoshop Elements does not have Contour.
You cannot use Photoshop to paint on the whiteboard. You need to use the built in painter.
It is question for Photoshop and Illustrator developers, which tool is from which app but Illustrator have Photoshop raster filters, that's for sure.
Photoshop Elements provides nearly the same functionality of the full version. It is neither easier nor more difficult to use.