I have 3 questions about a VPN and especially a VPN Router:
1) I know exactly what a VPN is and what wifi encryption (wpa/wpa2 etc.) is, but what I can't seem to understand is if a VPN Router will add more encryption on the wifi via a secured & encrypted private tunnel etc. If indeed that's the case so how does the mobile device "knows" to "talk VPN and AES-256 encryption"? It would have to have a VPN also installed on itself, right? From the router to the outside world it's obvious - it gets encrypted and sent through a secured tunnel to the VPN server(s).
2) When a device (PC, Mac, Mobile phone etc.) sends a request to the Internet through a VPN Server we all know what happens - on both ways - from our device to the destination we asked and back to us. BUT, what happens when you send something that is an account based app or service? Example: You send a WhatsApp message via VPN installed on your phone. Your message will be encrypted by the VPN (upon WhatsApp built-in encryption) and sent through a secured tunnel to the VPN server(s). The data is then decrypted and sent to the actual WhatsApp servers. So far so good. But what happens on the way back? According to my knowledge as an App Developer, WhatsApp servers will send the response through GCM/Push message or even their own Push-Messaging service but they will send it to my actual mobile device IP. Both Android & iPhone keep an open channel with Google/Apple and tell them the location and your IP for fast & power efficient push messaging. Also, when no internet connection available, Google/Apple will store all your messages/data and send it to you when possible, not caring, using and even knowing about your VPN. So all these messages and data from service providers like Google, WhatsApp and Facebook will actually send the data to my fake IP (VPN) and the VPN server will deliver it back to me?
3) I addition to question #2 - Is that possible for the OS itself (Windows, iOS or Android) to get my real IP even if I use a VPN? Cause if it so then a VPN will be useless for services like I mentioned in question #2.