Re: Concrete screeding
You can do it one of two ways:
1 - Set a form board a few inches away from the step that follows the contour of the step and pour up to it, but not past it. Screed off the fresh pour, then immediately pull the form along the step and finish the pour. Use the the first portion of the pour to set the height of the backfill.
2 - Make a screed board that has a hook on the end to accommodate the height of the step, meaning you know your pour height, then make a piece for the end of the screed board that will go up the face of the step and rest on top of the step. Kind of a Z shape. Use the face of the step as the form and the top of the step as your screed point.
If your pour is the width of the step and runs 20' out and away, then I recommend pouring the slab in sections so that it's easier to manage. Break it into equal lengths, such as four 5' sections. Pour the step area first, skip one, pour one, skip one. When the concrete is set, strip the form between the slabs and the open sections, then pour the open sections. This will allow you more access for screeding and working the concrete. You're also pouring smaller sections, which will be easier to stay on top of than a single, monolithic pour.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!