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homography vs SolvePNP for pose detection, how and why?

I have mutiple planar markers where I can detect 100-200 points each in a reliable manner. In each frame I see one or two markers at most; I need to calculate the camera pose.

I am not sure whether I should use solvePNP or findhomography for the pose detection.

1) OpenCV homography page states that solvePnp should be used for planar objects as well, and findhomography is just for demo in terms of pose detection. See https://docs.opencv.org/3.4.1/d9/dab/tutorial_homography.html On the other hand, solvePNP is using POSIT, right? Which should be less accurate on planar features, please correct me here if the implementation is actually taking care of the planar case. So, should I ever consider findHomography or not for pose estimation?

2) In case findhomography still makes sense, how should I use it? Should I use two frames and feed 2d-2d coordinates to the findhomography, or use the "3d object coordinates without Z" as the source?

Thanks for any hint.