No, you can not.
Go to the app store and use you iTunes card to get apps
No, you can just use your own credit card.
You can use an iTunes card for purchasing apps at the app store. Maybe your card still has a value of $40 because you downloaded a free app.
Nope too bad
No. You need an Apple App Card to purchase Apps from the App Store!
Yes, you can purchase gems for DragonVale using an app store card, as it allows you to add funds to your app store account. Once the funds are available, you can use them to buy gems directly through the game. Just ensure you have enough balance in your app store account for the desired gem purchase.
At the store
As a consumer, you don't start out with a 'freebee' or credit balance. Most App Store accounts have a credit card attached to them, and are limited only by the credit card's credit limit. If you use an Itunes or App Store gift card, it is a credit based on the value printed on the card. As a developer, you only make money when a paid app sells. You get 70% of the selling price you set. Apple gets the other 30% for hosting the app, approval and quality control and account management.
Yes, you can use iTunes Gift Card money.
Go to the iTunes store on your computer and click redeem, open the gift cards category. Enter the code on the back of the gift card. The from your iPod you can download the app or search it in the iTunes store from the computer and Sync your iPod afterwards.
To use a Suica card on an Android device, you need to download the Suica app from the Google Play Store. Once installed, open the app and follow the instructions to add your Suica card to the app. You can then use your Android device to tap and pay at Suica-compatible terminals for public transportation and purchases.