Will I be able to use my World of Warcraft discs on my Mac and PC?
Yes, the discs will be wow gold compatible on both Mac and PC.

Can you alt-tab in and out of the game?
Yes, you can also run the game wow gold in a window.

What forms of currency will there be?
Currently there is gold, silver, and copper. And in case wow gold you were wondering, there are a lot of things you can buy with your money, including training, equipment, profession recipes, profession components, extra space at your bank, and more.