It's pretty simple
I've seen quite a few people sigh at Hearthstone's recent iPad port rollout, because currently the game is only available in a select few regions, leaving a couple of major countries out of the loop (like the US).
But it's actually pretty easy to download it on your iPad in minutes, using a simple region change method that you can do entirely within your device.
First, just go into your iPad's settings app, select the iTunes & App Store tab, then touch your Apple ID and tap "View Apple ID". Select "change country or region" and change it to Canada, and then for payment method select "none." It'll bring up an address form -- just keep your name the same, and change the address and phone number to any Canadian business that has a telephone listing (they're generally easy to look up -- try the Bank of Canada).
Then select "next," go into the App Store, search for Hearthstone, and download the app. Wait for it to finish, then go back in and change everything back to your home region using the same method. Really, you could use any region the game is out in or any address, but Canada is just one of the easiest methods I've found.
Hearthstone is run off Blizzard's servers, so it doesn't matter which "version" of the app you have. If you're really nervous you can delete it when your version is released, then redownload it and keep all your data.