How many external screens can be connected to these machines, and how, and what resolution? If it's USB then all ports would be taken? I'm clueless about USB-C.

How many external screens can be connected to these machines, and how, and what resolution? If it's USB then all ports would be taken? I'm clueless about USB-C. Is it still possible to connect a hub for additional peripherals? I have 6x connected to my machine currently (external drives, printer, audio stuff, backup mouse, card reader), not counting extra screens. Really hope this works cause these machines look awesome.