Can Plane Shift be used to transport from mordenkainen’s magnificent mansion to the same plane the mansion was created?

The text of Mordenkainen’s Magnificent Mansion (mmm) states:

You conjure an extradimensional dwelling in range that lasts for the Duration.

Plane Shift states:

You and up to eight willing creatures who link hands in a circle are transported to a different plane of existence.

Can a party plane shift from the mansion to the same plane they where in when they created the mansion? i.e. they create the mansion in the material plane, go into the mansion and then plane shift to a new location in the material plane?

What are the limits of Mage’s Magnificent Mansions?

I am DMing true D&D for the first time. So far it has been one of the most fun experiences in my life. However, I have found myself in a bit of a pickle. Starting off I was very liberal in what I allowed my players to create and do, and now am seeing the problems of this break out in my world. So, now I am tightening the leash a little bit. One player in particular has a very powerful Rakshasa sorcerer and recently has started using the Mage’s Magnificent Mansion spell to create a restaurant and sell the food from inside. He is trying to weave a network of mansions from different points together to create a instantaneous fast travel system. The player states that the rules are genuine, but I’m not so sure it I agree. Are there any limits to the this spell in the rules? Can he have more than one mansion at one time and can his servants leave the mansion to act as staff in an eatery?

Would the Magnificent Mansion if cast on a moving object remain where it was cast or stay with the object?

The question has arisen in my mind on whether when a mage has cast a Magnificent Mansion (5e) while on an object that is in motion (boat, airship, giant alpaca, etc), would the doorway to the Mansion then remain static in place?

The relavent wording from the spell: "You conjure an extradimensional dwelling in range that lasts for the duration. You choose where the entrance is located. The entrance is 5 feet wide and 10 feet tall…"

I could see that this would indicate that the mage has chosen the location to be the giant alpaca and as such that is where the door would remain located. Or that the mage has chosen the place in space that the door is located and as such the door would remain there despite the alpaca continuing to move forward. Or perhaps something else might occur…?

What happens to items left in Mordenkainen’s Magnificent Mansion?

Recently, the question arose as to what happens when you leave objects you own in Mordenkainen’s Magnificent Mansion. The spell description does not specify if you always conjure the same Mansion, or if it is a different one. So what happens if I leave something like my magic short sword in it? Or even a mundane item, like my mundane pottery?

The spell says that creatures are expelled when the spell ends, and it says what happens to things from the mansion that you want to take outside, but there is nothing about items taken into the mansion. Is there any information in the rules, somewhere?

What happens to matryoshka Mordenkainen’s Magnificent Mansions?

The following situation happened towards the end of our last session(I am the DM): A player cast Mordenkainen’s Magnificent Mansion, so they could take a break to heal up their comrades and rest a bit.

Then, that player cast the Mansion again (after a long rest) and placed the portal inside the first mansion. Everyone went through before the first mansion disappeared, and expected to return to the main overworld again after another 24 hours.

But technically, the Mansion only expels creatures, not portals to extradimensional planes, so shouldn’t they be thrown out where the first mansion was, an extradimensional space?

I am not gonna do this to them now since this would be the end of the story and not something anyone expected, but still: Would my players be back to the extradimensional space where the first mansion was?

Can a Knock spell open the door to Mordenkainen’s Magnificent Mansion

Assuming that a Mordenkainen’s Magnificent Mansion is conjured and the entrance is closed, could a creature make use of the Knock spell to open the door to the mansion?

Would the gateway be not considered as an object that Knock can interact with?

Would the creatures get immediately expelled even if the entrance is open (since they were not designated to be allowed inside the mansion at the time of casting)?