Temperature control when I can't affect either airflow or thermostat
Get a carbon monoxide detector, and block of one or more of the non-bedroom vents.  This will force more of the warm air to your bedroom.  You can just tape cardboard over the vent or they make magnetic vent blockers that are pretty cheap.

I believe that you will be able to use a modern thermostat.  The wiring may be confusing but if you read the thermostat manual you can probably figure it out.  Save the old thermostat and take the new one with you to your next place.