Heating I would get a ceramic heat emitter with a dome holder and rest it in the middle on the top bars (it shouldn't heat the bars much if at all) and thermostat to keep the temp from going below whatever temp you pick, also make sure you have a thermometer in the cage to check the exact temperature. Therese a section called heating under housing and accessories if you want to have a look there. All hogs like different temps, so just keep playing with it until you find where she is most comfortable with being active, but dont let it got below 20c
I'd definitely recomend looking in the nutrition topic at the beginners guide to hedgehog nutrition - its a stickie I can put it as link if you need
You can cover up the back and two sides if you find it looses too much heat. By doing this you still get plenty ventilation but it will hold more heat.