You might get more responses in this forum: Gardening with Stone

Regarding the question of laying out the curve, it would be good to create an accurate, to-scale, measured drawing of exactly the curve you wish to construct. Divide the curve in the drawing into uniform segments -- for example, every 5'. Also, draw a straight line that connects both ends of the curve to each other. Using a scale that corresponds with the plan, at every uniform mark along the path of the curve, precisely measure the distance of the curve from the straight line and record this on the plan.

You'll be laying out the same drawing on the site. Mark out the end points of the curve with stakes driven into the ground. Run a taught string between the end stakes of the curve, connecting them the same as the line on the plan. While many people use a hose to lay out construction because most people have one and it kind of works, it has a lot of drawbacks. My favorite tool for marking out landscape features on the ground, both at the brainstorming visualization and in the construction preparation level, is the marking paint wand. The way to use it is to walk along spraying a paint line on the ground as you go. In this case visualize the general path of your curve. At intervals along that path, mark short paint lines across it at the same uniform interval (every 5'?) which you divided it into on the plan. At each interval plot out the same distance from the string line that you measured at the corresponding location on the plan and create a dot paint mark at the cross line that you made previously. Once you have plotted all the dots that represent the curve, use the marking to spray a curved, DASHED line connecting the dots. At this point, step back and observe the curve from different viewpoints and make sure that you are satisfied with it. This is the opportunity to make adjustments in your plan if you think the curve is not right. Once you are satisfied with it, paint over the dashed line with a solid line. This represents the limit of the actual field of paving slabs. As you can imagine, the line will be destroyed by the construction process. You'll need to make a second line at a measured distance offset from it that is out side the field of work so that you can keep a reference line for the curve. You could also pound stakes into the ground at close intervals if you want to mark the reference line that way. When you build the paved area, make it as perfect as you can, but there may be imperfections. If you can tell there is an error, others will see it, too. If you can't tell, others probably won't be able to tell either. You may not want to bother fixing small imperfections that no one will notice. If it looks perfect, it IS perfect! No one is going to study it with a micrometer. (Disregard that my drawing is not perfect. I didn't measure anything.)