The conduit shouldn't move, don't need to press down so hard on the screed to bite into it to make it move. I prefer a crisp edge 1x rather than a 2x4.
8' can work, just depends on the overall shape/size of the area and the pattern of pavers (e.g. some patterns want to lay out in a rainbow vs. a linear sidewalk). However you don't have to screed the entire length, just make sure when you slide it down you leave some overlap into the old sand (so slide it 6'). You should take the proper time to make your gravel base as consistent as possible, checking with a 4'+ level, which will minimize using sand to fill/cut low/high spots. Recheck sections of pavers as you go.
8' can work, just depends on the overall shape/size of the area and the pattern of pavers (e.g. some patterns want to lay out in a rainbow vs. a linear sidewalk). However you don't have to screed the entire length, just make sure when you slide it down you leave some overlap into the old sand (so slide it 6'). You should take the proper time to make your gravel base as consistent as possible, checking with a 4'+ level, which will minimize using sand to fill/cut low/high spots. Recheck sections of pavers as you go.
