eCart does not have a way to create the calendar, you would need to create this part yourself.
all of what you are asking about can be done, but most of it is not native to eCart, and will need some custom coding to accomplish.
eCart offers the ability to add items to the cart, and checkout.
The way the item catalog is defined is up to you, the catalog can certainly be event registrations, but the concept of minimum / maximum will need to be implemented by you. hiding and showing the event would also be implemented by you, you would use a recordset to look how many times the event has been purchased and hide or show the event based on that number.