Welcome to the Mac Family!
Your only option with your 2012 MBA is to use the procedure I described in
Post #7 above.
Within that procedure, you have two separate options:
Easy to install (one time only), costs more: Install Snow Leopard Server into Parallels. Parallels provides instructions on how to achieve this result.
Harder to install (one time only), costs less: Install Snow Leopard (client) into Parallels. Parallels does not support the installation of SL client, but my instructions, linked above, show how to achieve this result.
Parallels retails for $79, but can be obtained at a discount if you work to find them on the internet.
Snow Leopard Server cost $500+ when originally sold by Apple, but they have discontinued its sale. Recent sales on eBay have ranged from $51 to $94, which is the best price I have ever seen it on eBay (to date).
Snow Leopard (client) costs $19.99 direct from Apple.
Parallels offers a 14 day free trial download.
Although it works for me with only 4GB RAM on my 2009 MBP, I recommend you have at least 8GB RAM on your MBA when using Parallels to avoid sluggishness and slowdowns.
You may never bump into anymore PowerPC applications to run on your Mac (except perhaps for other games), as they are now 7+ years old and many have been updated to run on an Intel Mac. However, with Parallels installed, you will have the option to install Windows and be able to run that operating system and its applications on your Mac, as well.
NOTE: Parallels can be easily made to encompass the complete screen of the MBA (click on its green button); it is shrunk down here to show both environments (Snow Leopard & Lion, in my case) running concurrently
[click on images below to enlarge]