RTL SDR Hardware Architecture

Hello to all, I am an electrical engineering student from Brazil and I have already been studying GNURadio using RTL-SDR for a while (I have an EZCAP dongle). This is my first post here. I am studying the basic FM receiver and my question is: Which is the actual receiver architecture used in the RTL-SDR dongles? I mean, do we have a Hartley receiver, a Weaver receiver, a zero-IF receiver, a low-IF receiver? Also, the E4K tuner has two outputs: one output is the in-phase component and the other output is the quadrature component. So, does the RTL2832U has two ADCs to sample the two components? Or just one ADC and it samples the two components interleaved? Thanks very much in advance, Lucas Ingles