I am going to finish adding a set of switch back stairs to my deck. The 4x4s post will be attached on the out side of the stringers and landing. The stairs are 39.5in wide. I am trying to decide how large to make the landing and where the railing posts would be located. After drawing it out, I think the option to the right is the best but appreciate any comments. Drawing isn't to scale. I believe the landing needs to be atleast as wide as the stairs. I was going to make the length of th landing 2x the stair width plus room for one baluster. Am I missing anything obvious?

So I have removed the broken deck and want to build a new one, with the same dimensions but I have a problem. 1. My deck is below 24" so I dont need a permit (like the old one). My hight over the ground is 18". from the patio door. If I calculate down I am going to use 5/16 for the decking, then the joist then the beam. (using 2 by 6) I am getting 7 1/4 for the post size. But the internet search shows that the post should be at least 12" in order not to split it when I connect it to the beam. What should it be? 2. I already have concrete pads from the old deck, but they have an overhang of 3ft 1/2, and the code in Winnipeg says that it should be 2 ft but only if it has a roofed structure over it. I am planning to put pergola, so no roof. But I still do not understand can I reuse the old pads? or they are located wrong?