Re: deck stair
If I understand you correctly, you're saying that the landing where the stair terminates is not level. What I've done in situations such as this is to cut the foot of the stringer to the fall of the landing. In addition, I like to use a piece of composite decking (Trex ) under the foot so that it gives me a place to anchor the stair to the landing as well as a non-wicking base for the wood stringer to sit. This will reduce the proclivity of rot to set in.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!