Second question, your return registers may be sucking up the smell and circulating it all over the inside of the home.
Call your locale steam carpet service providers in your area for assistance. I have heard that they have equipment and a process to rejuivinate a home that has been on fire. Removing smoke smell is just as bad as your situation.
You have done alot to assist in this situation. I would also add, tossing boxes and boxes of baking soda all over the place. You know people use it in refrigerators that have had spoilage in them. I use that to mask my sent when I go bow hunting.