Would it be possible to use these serial enabled lcd's in conjunction with i2c port expanders to increase the number of LCD's
You don't need (or want) serial enabled LCDs when you use an I2C port expander, the port expander does the serial enabling part for you.
I bought a few MCP23018 port expanders ...
but I'm having trouble grasping exactly how they would work in conjunction with the LCD's.
Since the LCD's I'm using have up to 8 changeable address, would that mean I'm limited to 8 LCD's per bus ...
... rather than 8 LCD's per port expander?
Is it possible to set up a sub-addressing system to get around this?
How many buses can I run on a single arduino?