Hi, a simple way to look at things is that the Public folder will be available to anyone that has access to your home network, there is no option to limit access. If you need to limit access to specific files, you need to create a private folder and a user for the person that will access that information. To access the My Book Live from your iPhone and the Android tablet you can use the WD2go app. Check the links below for more information.
Creating a new user
http://wdc.com/wdproducts/library/UM/ENG/4779-705058.pdf#page=80
Creating a private share for a user
http://wdc.com/wdproducts/library/UM/ENG/4779-705058.pdf#page=82
How to access files on a My Book Live using WD 2go on a mobile device
