Does the USB-C expansion card support video output? I have a USB-C to DisplayPort cable and hope to connect to external monitor using a USB-C port on the framework laptop. Is it possible? This is important to my purchase decision since I will have to pick a DP or HDMI expansion card if there is no video output support on the USB-C card. Thanks!
Yep, the USB-C Expansion Cards support DP Alt Mode for connecting a monitor.
Does DP Alt Mode support Multi Stream Transport (MST) to daisy chain multiple displays?
Yes, MST is supported.