Focus LCDs

Yes, changes in temperature can change the contrast and it may need to be modified by the user. Some products contain a setting to adjust contrast.

The simplest type of monochrome is a segment display with a 4:1 mux or a 1:1 mux. There are many controller/drivers on the market that make it easy to program.

Character monochrome displays contain a built in controller drive with a character table to make them quick to program.