Re: accessible from grade
I am going to ignore "Charlie's Rule" for a moment (GASP!

), and try to discern the intent of the article under discussion. I believe the intent of requiring a receptacle at the front and back entrance is to permit the homeowner to operate an electric mower, weed-whacker, or trimmer. It is all about gardening. You are going to be standing on the grass, when you cut the grass, and you want to be able to reach the receptacle. If you have to run your extension cord up the porch steps, that is going to create a possible tripping hazard (for people sitting on the porch) and a possible pinching hazard to the cord itself (if you have to run it through a porch door). There might be no such hazards, if the "porch" is but one step up from the grass and is only 4 x 4 feet in size (no room for a chair). There might be no such hazards if there is no door that might close on the cord.
I think this is one of those code-writing instances of "we can't cover all possible cases, so we'll make a rule that is more restrictive than may be needed in some cases, just to make sure we provide for safety in the other cases."
Now back to the rule itself. I see no difference in the meaning of the word "at" and the word "from," as those words appear in the two separate sentences. It is bad technical writing to use separate words. But the fact that two different words were used does not compel us to interpret the two words differently. If you can stand on the grass, and reach up to plug a cord into a receptacle that is above the porch, then the receptacle complies. If you have to walk up steps, because you cannot reach the receptacle while you are standing on the grass, it does not comply.