How does everyone go about setting up the depth at which they present thier bait this rig.

I normally take the line and measure out one arms length and that's where I put the hook.

Anyone noticed a change in the quality of fish they catch on a Drop Shot based on whether the bait is sitting a higher or lower area on the main line?

it all depends on bass, i usually leave 2 foot tag line, and adjust from there

Leader length is generally based on where the fish are for me. If they're right on the bottom, shorter. If they're suspending, obviously then you want it longer.

Start long, then cut down as needed after you've located some fish on the graph.

I fish a double DS now I have the best of both worlds!

I fish a bubba version of a drop shot much more often than a traditional light line version. An 18 inch leader would be long for me and much more often it is a foot or less. That seems to work the best for me.