Does anyone know (or know of a website that shows) the required/recommended size of the brick surround area for a wood burning stove? IE: How far out from the sides and front should the brick extend?

House built 1975. Concrete pad, 12'd x 18'w. There is a large crack, 1 inch wide, that runs the entire width in the middle. The cause appears to be settling of the ground against the house. The half against the house is now angled down, thus any water accumulation on this half is against the foundation (concrete). As far as I can tell this hasn't created any problems in the basement yet. We would like to increase the height of the pad so that it is level with the first step, about 5". Questions: 1. Can we pour over this existing pad? 2. Should the crack be repaired first, and if so, 3. What is the correct technique? Eventually we would like to cover this pad, and/or enclose it. Any other thoughts/comments greatly appreciated. Thank you