Removing Slate Wall Tile Slate Tile?

Slate tile? - removing slate wall tile

I am trying to remove an existing wood fireplace surround (no fire), but some decorative wood around the fireplace, and 70 of the chimney, and replaced with slate tile Nice.

Slate is fastened to the wall and floor. Is there anything I should know, if you (Slate), in conjunction with tiles on the wall? Is it necessary to remove all the paint, or I can put a sticker that mix (link PL Premium or regular mortar?) To get.

How far should the joints with the slate? I know you want to close with marble, ceramic can have a place.

How the tables are to ensure no "slip" when she joined a vertical wall.

Sorry for the questions, but they realize all the suggestions and answers!