Instead of using libraries, they use their own solutions for pretty much everything they can, so they expect the mobile dev to know of some rather low level details of things such as network requests, since their implementations require exposure to the details.
The process took 4 weeks. I interviewed at Visa Inc.
Interview
It was a simple telephonic round on the basics of android and work experience. Telephonic interview typically lasted around 30 mins on General mobile tech stuff and basic android question. The interview was not hard.