A:AnswerYes! Actually, I did it when I bought mine. I found it a little bit cheaper at a known online store and the Best Buy cashier matched the price, no questions asked. They are great at this match up thing!
A:AnswerYou have to create an online account with Zagg. Then register the product. Then there's a button that says something about warranty. You just pay for shipping. Keep the cracked one because you have to send it back or they'll charge you full price.
A:AnswerYes! I drop my phone all the time and my screen has yet to crack. The screen protector has gotten beat up, but the actual phone is pleasantly safe!
A:AnswerYes you should be able to use it with any case. I have used an Otterbox in the past and had no problems. I am using a different type of case now and it works great as well.
A:AnswerThere should have been instructions on how to register your product with Zagg. I would think that Zagg would replace it for you. See the following link for info. http://www.zagg.com/support/faq