Starting with Premiere Elements 9, Adobe offered a Windows and a Mac version for Premiere Elements.
1. Premiere Elements Windows projects do not work in Premiere Elements Mac and vice versa.
2. There are many Premiere Elements features that are Windows Only. Few examples...Premiere Elements Mac does not offer Chroma Key, Green Screen Key, or Blue Screen Key. It, like the Windows version, has a Videmerge effect which is often recommended to the Mac users as a substitute for the "missing". I prefer not to use Videomerge.
3. There are several other components that are Windows Only. I am strictly an Elements Windows user, and a while back I tried to gather some information on Premiere Elements Windows - Mac
Does Premier Elements 12 work on a MAC?
If all you want to know is whether Premiere Elements is sold in a Mac version, your answer is yes. But, if you really want to know if Premiere Elements Mac on a Mac computer will work for you, that is another matter. Instead of directing you to a place of purchase, I would suggest that you download and install the free 30 day tryout of Premiere Elements 12 Mac and detemine if it is compatible with your specific computer environment, the properties of your source media, and your video importing, editing, and exporting needs.
Please review and consider.
I did not see your post numbered 2 until after I had posted my post numbered 3.
Again, I would encourage you to go the Adobe free 30 day tryout of Premiere Elements 12 Mac before any purchase.
If you are happy with the tryout results, you can consider purchase from whomever gives you the best price.
Even if you look at the Adobe tryout, you do not have to purchase from it. One scenario is to leave the tryout installed
and just insert your purchased serial number from Adobe or from an authorized reseller, whomever has the best price.
But consider, if you go between Premiere Elements Windows and Mac, the download purchase will get you files specific to the computer operating system being downloaded to. If you purchase the box packaging from an authorized reseller, you get installation discs for Windows and Mac.
More information and clarification if you need it.