Heating And Cooling
The most important part of heating and cooling goes back to how well you insulate the container, my guess is the better the job the less energy need to heat and cool.
For larger place I would consider making it a Passive Haus, and include a heat exchanger
Basically the warm air going out heats the cold air coming in and vise versa, a well insulated passive hause will hardly need any additional heat.

One idea I had looked into is Geothermal for cooling.
A trench dug deeper than 6 feet and as long as you can make it with just a coil of pipe laid in, this would use the stableized cold ground temperature to cool air in pipe, the longer it travels threw pipe the better its going to cool, anyway a simple connection to the front of container, once drawbridge is down and a small fan you can suck the warm air from ceiling height threw the pipe and return it as cool air, very simple but I think it will work in a small area very well.

A simple heating method providing you have some sun is to use a solar heater, I have made one from soda cans that works very well.

A very simple A/C unit made from a frozen water bottle would provide a short term fix to cooling.
Another great heat source is the Rocket stove, although I dont like the idea of a fire burning indoors
but I have Sean examples where these type of heaters can create a lot of stored head by using stone benches and passing the neat threw them and retain the heat releasing slowly into home. would be great in very cold regions.
Very simple fuel fire is using Ethanol, it burns clean with no fumes or smoke and gives out a good heat, I have one in my apartment.