Yes, you can buy apps for the iTouch using an iTunes card.
Do you mean an iTunes gift card code? If you do, a gift card code is when you have an itunes account, but its not hooked up to your credit card or debit card (money wont be taken out of it for buying a song) Therefore, you need to buy an itunes gift card from the store and reedeem it on itunes. (the code is on the back of the gift card) However much you spent on the gift card, thats how much money goes into your itunes account, so you have to keep buying them if you use all your money
Apple have not made ten billion apps but they are about (at the time of writing) to sell the ten billionth app from the App store. They are offering a $10,000 iTunes Gift Card to the person who downloads the ten billionth app. (See links below)
The price you want it for. If you want to buy a five dollar card, it's five dollars. If you want a ten dollar card, it's ten dollars.
The 10 billionth song, "Guess Things Happen That Way" by Johnny Cash, was downloaded by Louie Sulcer of Woodstock, Georgia. As the grand prize winner of Apple's 10 Billion Songs Countdown contest, Louie will receive a $10,000 
iTunes Gift Card.
an ipod touch
No, but if there are no accidents, we get a ten dollar gift card every month.
In order to get a thousand dollar gift card, you have to speak the a salesperson or manager of the store to see what things they offer. You may have to buy ten $100 gift cards. That is probably an easier way to get $1000.
Amazon has several methods for people to purchase items with. If a person has not debit or credit card ten they can use an Amazon gift card.
Most denominations of ten, such as $10, $20, or $30 or good dollar amounts to put on a Chili's gift card. $20 is recommended to purchase most meals from the restaurant.
It definitely depends on who you're giving the gift to. Here are some ideas that will probably work for almost all ages: -American Express/Visa gift cards -iTunes gift cards -Jamba Juice/Starbucks gift cards or gift cards to a favorite store. For children: -candy -toys -board games Hope this helped!
it is listed daily on the itunes homepage