Advice on retiling and extending fireplace hearth – GreenBuildingAdvisor

I’m getting ready to retile my hearth, in part because I have to extend it out 7 more inches to meet code. I’d like to avoid cutting out the wood floor so plan to lay a 1/2 inch of micore 300 over the top of it, and then add cement board over the micore, and then tile. 

I will be removing the existing tile and then adding two layers of cement board so that they are flush with the 7 inch extension of micore and cement board that I’m adding. 

I plan to put 3×6 porcelain tile over the cement board. My questions include

1. I assume that I can just screw and glue the micore to the wood floor. 

2. Any tips on getting the tile out from under the mantle without damaging the mantle?

3. Any tips on cutting cement board and tile so that they fit under and around the mantle? 4. Any recommendation on what kind of cement board to use? 

Thanks for any feedback our guidance on this.