Thanks for your replies. I ended up calling support and got a reasonably prompt call back from Ashley.
Based on her advice, I did combine the two COM wires (which BTW when twisted together are hard to get into the COM slot). Had to make a trip to Home Depot to get a wire of similar gauge so as to extend the pair.
For the rain sensor, she also advised to combine the RED (anyone of the two) with the white wire and put that in R1. The brown wire in R2 and the remaining RED wire in COM. In doing that had a lot of trouble getting the thinner gauge wires in as they bent. Had to twist them with a thicker gauge one to get them in the slots.
Thereafter, I powered up the Iro and was happy to see lights. I could not get the outer cover to flush with the base unit (see picture below). The data/power connector on top appears to be connected as the Iro is functioning. I tried to apply reasonable pressure for it to be flush but gave up after a certain point for fear of applying too much pressure. This part I am not too happy with.
I downloaded the app which seems to be decent. I was skeptical of the blinking programming option… but got it in the first go!
During the programming for the 12 zones, initially there is a per zone test with a countdown timer. The way the app operates, i felt it did not give enough time for the sprinklers to come on. I thought I had some misconfiguration since none of the sprinklers came on. As I walked over to the couple of the last 2 zones did I realize that I had to wait longer.
Thereafter I rechecked the wiring and manually verified the zones.
Have now setup my bi weekly program in place. Somewhere in the description of the product there was a reference to integration with Nest units. Is that an upcoming capability ? I did not see anything this version of the app pertaining to that.
Thanks for all the replies