Should I complete all interior painting before or after laying ceramic floor tile throughout?

I have just removed the old tile in front of my fireplace. Under the tile was some "crumbly" concrete. I removed all this, and what I am left with is a 1 1/2" depression, with a concrete slab at the bottom. Do I fill the depression with concrete and allow room at the top for hardibacker and tile? Do I bond the hardibacker to the concrete? Do I allow for expansion/contraction of the hardwood floor around the depression by leaving a air gap betweeen the "new" concrete and the hardwood floor? How does one deal with the tile to hardwood floor joint, where the tile butts up to the hardwood floor? Thanks, Lou