WhatsApp introduced Chat Lock a while ago, but version 3.3.10 refines the "Secret Code" feature. You can now set a unique password (different from your phone unlock) specifically for your locked folder. This makes it much harder for someone with your basic phone PIN to snoop.

: Beta testers have frequently been used to test the ability to listen to a voice message before sending it.

A: Only if you are in Apple's TestFlight beta program. Apple does not allow direct APK-style downloads. Unfortunately, TestFlight slots fill up within hours of opening, so availability is extremely low.