For the smell, try any air purifier that generates ozone and it will kill the smell very quickly. Here is a link to the product I use. http://www.alpineairproducts.com/
Filters don't work well unless ALL the smoke passes thru them and even then, not so good.
And as far as protecting the floor, I have tried using a cookie tray but the problem is, if you drop a coal, it is likely to bounce off and land on the carpet anyway. But a nice large carpet won't have that problem. If it is just ash you are worried about, then a cookie tray works great.