Hey Steve, Welcome to the Fourm:
Forget the tar paper, that's what we used to use as a vapor barrier before polyethylene was widely available.
A laser level will be a tremendous help to you in installing the sleepers. If your concrete is 2" or more uneven you need to consider another method of installing the sleepers. You could use a full band around the floor, get your layout of the sleepers, chalk lines for each sleeper, take measurements every foot along the chalk line, transpose those measurements to a 2 X 4 and rip it down to the measurements. This throws out the shims but the sleepers will be in full contact giving full support for the sleepers.
Also, may I suggest the use of underlayment grade, tounge and groove oriented strand board, glued to the sleepers and the T&G. You will defeat a world of squeaks by using the glue; I recommend Contec P L 400.