SD Quattro kit able to print large files as well as the Nikon D810?

Hi everyone, I'm sort of new here on this Sigma forum. I said pretty new, because a few years ago, I was here asking about the older Sigma DP cameras (not the Merrill) when I had the Olympus E-PL1 (12MP) and wanted to know if I could get really sharp and detailed prints @ 16x20". Some knowledgeable members then (some names I don't see here anymore),I was told yes and at that time, I was really impressed with the Foveon sensor and was just planning to get a used older Sigma to complement my E-PL1 for just a few specific needs. And then, I saw a great deal on the Sigma dp1 Merrill, but when I tried it, it was very slow and difficult to use. So I decided then to just upgrade my E-PL1 to the now E-P5 using the funds I saved for the Sigma.

I shoot mainly with my Panasonic 25mm f/1.4 (50mm eqv) 90% of the time for all landscape and urban landscape stuff and about 10% of the time with 14mm (28mm eqv) with my MFT and love the print output up to 16x20". But when I tried to enlarge it to 24x36", it lacked the sharpness and the detail that I saw with 16x20" prints. I used to be a pro a few years ago before I retired and switch to a different career and when I had my Nikon D810, I remembered that I could get great 24x36" or 30x40" prints that had exceptional sharpness and detail. I missed the ability to do that, but right now, I don't want to invest in the D810 again as I'm doing this as a fun hobby. Which is why I am interested in the Sigma sd Quattro kit because it is very affordable @ $800 on sale or maybe less? I will probably get the 20mm lens latter after I saved up enough to give me the 30mm eqv wide angle. I was thinking of adding the E-M1 II, but this is a much more expensive camera than the Sigma kit and has a lot of features that I won't use.

Obviously, I will be using the Sigma sd Quattro as a one trick pony @ ISO 100. When I'm shooting landscape with my E-P5, I have it on the tripod with my Panasonic Leica 25mm lens (which is pretty sharp) and do it really slow and meticulous to get exceptional sharpness and detail. So with Sigma, it will be no problem. I'm not planning to use it at any other ISO; maybe 200 or 320 handheld as I saw the RAW samples and the noise or grain are sweet and beautiful.

So here's my questions:

1, Does anyone have any experience comparing prints between a 16MP MFT camera with a Panasonic prime lens against the Sigma sd Quattro with kit lens and see a big difference in the amount of detail captured and printed @ 24x36 and up?

2, Does anyone know if the Sigma 30mm f/1.4 kit lens that comes with the sd Quattro has focus breathing? This is essential as I do quite a bit of focus stacking with images I captured using Helicon Focus.

3, Does anyone know if Super Fine detail mode in the sd Quattro that captures 7 images and then merge them together has any issue with moving subjects like water or clouds when doing long exposures?

4, What is the approximate dynamic range of the sd Quattro compared to the Nikon D810?

5, What are the used prices of the sd Quattro kit going for now?

Basically, the purpose of getting the sd Quattro is to have a camera and lens that I can capture scenes that I think it's worthwhile printing big and while my E-P5 is plenty capable of making gorgeous 24x36" prints, I miss the ability of my former D810 and its files that can pretty even better detailed prints at the same 24x36". I just needed some confirmation if I'm making the right decision to go the sd Quattro route.

Thank you..