Room Air Conditioners…

It seems as though we use our Air Conditioner my Wife complains of Headache etc.

to be done legally and safely…
it has to be done at a licensed facility that is equipped to recover freon from those products
they have special machines that they use to recover the freon so none escapes into the environment

I am building a room on to my home, and we are kind of having to build it around the air conditioner unit outside. It is on a cement slab and is about 5 feet from the house. Would it be ok to build a room around this unit? It will be completely open on top, but surrounded on three sides with building that is 8 – 10 feet tall. How far away from the unit should the room be? How much room does an air conditioner unit need to function properly?

How to service?
What doors in the house do we leave open of shut?
What temperature to run it at?
How to get the best performance?