Can I transfer all my WhatsApp info (contacts, chats, photos, videos etc) from my Android phone to my Lumia 1520?
No, you can't transfer all your information from Android to Windows Phone. But you can transfer most part of it. Contacts are linked to your what'sapp account, so you can transfer it in some way. Photos and videos can be transferred through Bluetooth, or even manually coping and pasting using a PC. But chats, there is no way to transfer it, because you need to verify your what'sapp account every time you change the device you are using. I use a Windows Phone and a Android device, and use then alternately in a two weeks routine. What I've notice regarding the chat is that the chat history continues from were you left on the same device, so the conversation kept in my Windows Phone will be from two weeks later and vice versa for my Android device.