See after bullets..... and use blown in insulation or tear the sheetrock down and reinsulate with fiberglass insulation. •• No contest. Blown cellulose hands down.
Also what would be a good way to check if its poor insulation? •• Some energy auditing places have thermal imaging equipment to take a picture of your house and show you where the heat is getting out. It costs, but so does cutting holes all over the show.