Yes, they should fit in this can.
Yes. I have multiple USGI mags with ranger plates attached. And PMags both M2 & M3 all with ranger plates. You may have to slightly nudge just a couple to the side slightly where the top is lower in certain parts? But that’s about it. They still fit fine. I store my mags empty and upside down. I’m not sure that they would hold it with loaded mags and ranger plates? It would hold them. I’m just not sure it would hold them while maintaining the O-ring seal.
Yes. They do. I turn my mags upside down while empty and it works fine. But, I have multiple of these cans full with both M2, M3, and USGI mags all with ranger plates on them. Many have lids too. (The PMag covers) They all fit fine. Pro tip though? Sometime you may have to slightly nudge the mags in certain areas to lean a little to one side to get the top to close right. It’s not a big deal. But rather than have all the mags exactly vertical? Just push the two in the corner or wherever slightly off center. This is because certain parts of the lid are a little lower. But, I do have these cans filled ENTIRELY with mags with ranger plates and they fit and close fine. Definitely recommend.