Don't cut the sensitizer for the second coat; it needs to be full strength.
I did some comparisons at one time and it seemed that the first coat could be cut with H2O, but it all depends on your methods, etc. If you have a particularly dark print, you may want to do it full strength to help beef up the shadows.
Double coating is nearly impossible to do well with a rod. I was never able to get a finished result that I considered satisfactory until I tried the Richeson brush that Clay mentions.
I air dry the first coat completely, and then use a hair dryer with low or no heat for the second coat. I let the second coat sit for about 5 minutes, or until it has lost the wet surface look, and then blow it mostly dry. Then I leave it for about 30 minutes to finish drying, and to allow it to equalize with the RH in the darkroom.
Works pretty well for me, but I'm just a hack with all this pt/pd stuff, so your mileage may vary.