i live in western ny and would like a little advise on a footer and concrete block construction of my proposed front porch - with flag stone top. i want to prevent any possibility of heaving.

aerial view is 10' X 10' --- top slab including the treads. i was told to dig down 40" --- 8" for the footer and three courses of block to bring it up to grade.

how wide and what shape should the footer be? should it be placed inside of the 10x10 perimeter? should a slab be installed at grade level before installing the stairs?

the vertical drop from my front door to grade is about 27"

any ideas would be appreciated.....

pw from chautauqua, ny......