Multiple Serial LCD control with Keypad Select

We have the Arduino Mega 2560, Newhaven Serial LCD displays NHD-0420D3Z-FL-GBW-V3 and Parallax 27899 4x4 Matrix keypad.
The plan is to utilize 9 of the displays and change the predetermined text with numeric keypad inputs.
What would be the point to point connections for all displays, keypad and Arduino?
The displays communicate either RS232 TTL, SPI or 12C.
What would be a good starting script?
I have never used a processor and display and am just getting started.
Any and all help would be greatly appreciated.
Thanks in advance.

I'm too lazy to check the LCD specs to see if you can assign an I2C address. If so you can put all 9 on the I2C bus.