For text terminals the only use of color is to differentiate text and this advantage is not always worth the cost of worse resolution. Thus monochrome may be better since it also costs less. For dual sessions the terminal has two serial ports of equal status. Each port is connected to a serial port on a different computer. Thus one may log in to two different computers with each session displaying in a split-screen window.
Many terminals have a connector on the rear for such a port.
Some printer ports are for parallel printers while others are for serial printers. If a printer is connected to the printer or auxiliary port, then pressing certain keys will print the screen. One may also have everything that displays on the screen go also to the printer. If the port is an auxiliary port, one may connect this to another computer and almost have dual sessions as above. However, the video memory inside the terminal may not retain both sessions so you may need to refresh the screen when switching to the other session.