I'll take a stab. I am fixing my sister's iPhone 5. I already have iCloud enabled on my iPhone 5. So, I just entered my Apple ID into iCloud on her iPhone. Then it asked if I wanted to merge Safari data, reminder and contacts on this iPhone . I chose no since i didn't want that, and had nothing to do with Apps apparently. Then I went to the App Store, then the Updates Tab. I see all the Apps I have downloaded with an iCloud symbol that are not on her iPhone 5 yet! In the Settings, under iCloud still, I noticed the Documents & Data tab toward the bottom is set to ON. OK. I just downloaded a new App on my sister's iPhone, and almost immediately I received a message on my iPhone notifying me of a purchase on my iTunes account, and that if I want to have automatic downloads, I need to go to Settings, iTunes & App Store (toward bottom), then turn ON the Apps in Automatic Downloads. The Updates is there for the Apps as well if you want auto-updates as well. With that, the Apps bought on another device should show up and download. Just did this experiment. I hope it works for you.