temp throughout the house will not deviate by more then 2 degrees from
Good luck with that one.
Thermostat location is always a difficult choice. You cannot have it to close to an opening like a door to the outside because every time you open and close the door the thermostat will be activated when actually not necessary.
Usually a location somewhat close to a cold air return is good. That is because on a properly designed system the sample at the return air will be a combination of all outlets but remember we do not live in a perfect world.
If you really have to control the temperature that close I suggest you spend the $$ to have temp sensors installed in all areas then let the computer in the thermostat make a judgement call as to when to activate the system for proper comfort. See example of a company that makes a system for this purpose at the below link.
Venstar Thermostat Accessories Venstar Thermostats and Accessories - VenstarThermostats.com
Ventstar has a great system for this purpose and it is designed to work with there remote control thermostats. I also have the Comfort Call system that allows you to call on a regular phone or cell phone to adjust the temperature by remote control. I find it very useful and a great accessory for the times when I am going back home from camp. I can call the house from my truck and start the cooling process so when I arrive it is just perfect.
A single thermostat should not be able to control your temp within 2 degrees in all the rooms on the same floor. I think you are asking a bit much from your contractor. Now if you spent the extra bucks and had a Manual D and a Manual J done on your house by an HVAC engineer you could get very close to your wishes. Sorry to say that costs a bit extra and the fancy kitchen cabinets or some other item you wanted burned up any extra $$ that were left. This is the normal situation in any house weather track or custom it makes no difference more money is spent on items you can see and not the HVAC system that is hidden.