Knock down a wall.... what to do?

Hi All, We have a gas fireplace in our family room in our townhouse. In the whole house when we come to the family room we can see that we are pretty much sitting outside (its deadly cold) even though other parts of the house is relatively better. When i pay attention, i can see that the cold draft is coming entering house from bottom of the fireplace.When opened the foot door of the FP, i noticed that the draft is coming from the whole where the gas pipe is entering the FP. I am attaching the pictures. [url=http://picasaweb.google.com/anikat/HousePics?feat=directlink]Picasa Web Albums - Anika - House pics[/url] For now i covered the hole with a thermocoal sheet and it feels little better. In my whole hose this family room and the basement appears to be literally standing outside, irrespective of my heat setting. Especially when the outside weather is soo cold. Cold draft is as good as i am standing outside. That to me is something really wrong as nowhere in the house it should feel like i am standing outside. Can you guys please throw some pointers what could be the reason. Could something be wrong with chimney and the cold draft is entering the house? I also noticed that my attic has 2 -3 windows like things that is almost like holes to the outside. But it looked like its by design. I am not sure if that could be a reason the draft entering the house.

My house was built in 1949 and I have plaster walls over some kind of wire mesh. Under that is the equivalant of modern sheetrock except it has preformed holes every 6" or so so the plaster could squish out and hold it tight to the wall. This must have been a transitional method of construction that happened as the use of lath fell out of favor but just before modern drywall construction (lucky me!!!). Anyway, can anyone help me understand this technique better and what was it called?? The wire mesh really makes repairs, forming new outlet box holes, etc. difficult. And the plaster makes hanging pictures, etc oh so much fun. -Jack