If you are looking to purchase a windows 8 phone online then the best place for this is ebay. The prices can range from $100-$700 for one of these phones and takes 5-30days for delivery.
As of 2013 the catalog of Windows 8 phone apps has not been made available on the Windows 8 OS.
There isn't any Windows 7.8, but if you were referring to Windows Phone 7.8, it cannot be updated to Windows Phone 8 (note that I did not say Windows 8 because Windows 8 is for laptops, desktops and some tablets).
No. Its a phone app not Windows 8 app.
Yes but you would need to pay a ten dollar fee to support the windows phone 8.5.
Yes, everyone that has Windows Phone 7 can download a string of updates through Zune (updates are installed cumulatively) leading to WP7.5. When Windows Phone 8 is released, you will get a toned down version of Windows Phone 8, called Windows Phone 7.8. This includes some key features such as the updated start screen, but not all of the features that come with WP8
You can find the Windows 8 Operating System on the Microsoft's website.
Any sound/audio clips will do as ringtone in Windows 8 phone. Just put those sound clips as your ringtone. You can also download App ringtone from Windows 8 store.
There are several apps for the Windows phone that aren't available at the Windows store for PCs, including certain games.
Windows phone look great and seem to have a lot of good features. The biggest problem people find with them is that the windows phone market does not have a lot to offer. A great windows phone is the HTC HD2.
Yes, the Windows 8 phone app store has many apps that you can download, but Google Play comes pre-installed on your phone.
I have windows 8 too. All you have to do is windows button+r then type in %appdata%
Keep pressing the power button.