Epic have answered many of your questions in a Reddit post. We have added them here and if there are any other questions you have, feel free to drop them in the comments section below:
With the announce of Fortnite Mobile, we put together an FAQ to answer any preliminary questions you may have:
Q: How do I sign up to play Fortnite on mobile?
A: You can sign up at http://www.fortnite.com/mobile.
Q: Where can I find more information on Fortnite coming to mobile?
A: You can read more on our blog at http://www.fortnite.com/news/mobile-announce.
Q: When can I play Fortnite Battle Royale on my iOS device?
A: Once the event begins and you receive an invite. Invites will start rolling out soon to players who have signed up.
Q: Why haven’t I received an invite?
A: We’re sending out invites as our services scale up to handle more players with the goal of maintaining a healthy player population. Not everyone will get in at the same time. After you sign up at www.fortnite.com/mobile, you will be notified via email once you get in.
Q: My friend received an invite and they signed up after me, what gives?
A: Factors that contribute to the order in which players receive invites include sign-up order, proximity to a data center, and device model. If your friend got invited by Epic, check with them to see if they have a friend code to share with you.
Q: Is Fortnite on mobile coming to Android?
A: Yes. Android will be supported in the next few months.
Q: What iOS devices are compatible with Fortnite on mobile?
A: To participate, you’ll need an internet connection and iOS 11 on at least an iPhone 6S/SE, iPad Mini 4, iPad Pro, iPad Air 2, iPad 2017 devices or later.
Q: Will Mobile players be forced to play with other platforms?
A: No. By default, mobile players are matched against mobile players only. When a mobile player joins a squad with friends on other platforms, then that squad is matchmade against a multiplatform population. Thus, cross platform play is opt in.
Q: I got an invite, where do i download the game?
A: In the invitation email, you will receive a link to download the game from the iOS App Store.
Q: Will Bluetooth controllers work?
A: Not initially. Bluetooth controller support is coming later.
Q: Is Save the World coming to mobile?
A: No. Save the World uses way more memory and CPU resources than Battle Royale and would be very difficult to bring to mobile devices.
Q: Will the game eventually be open to everyone, regardless of having an invite?
A: Yes. As soon as we are able to handle the scale of players, the game will be open to everyone.
Q: Will there be voice chat?
A: Not initially. Later, we plan to support voice chat.
Q: When do friend codes get sent out?
A: Friend codes are being sent via email separate from the original invite email. There is no currently announced time.
Q: When is the next wave of invites?
A: Unknown, but invites will be throughout the next few days/weeks.
If you haven’t signed up for mobile already, you can find the details here.
UPDATE: For those asking, Fortnite Mobile is NOT compatible with iPhone 6, 6 Plus, 5S, or earlier.