Download Apps on loaned iPhone
Login with your AppleID in Settings &gt; iTunes and App Stores and then run the App Store. Look in the Updates &gt; Purchased tab for all the apps you can download. 

In-app purchases can sometimes be re-enabled, but not all app developers handle this. Your milage may vary.

Make sure you go to Settings &gt; General &gt; Reset and Erase all Content and Settings before you turn in the loaner.