Finally I installed the buffers. It was a DIY project. The things needed apart from the buffer was cable tie and WD-40 and both of them were optional.
I took the car to the service station early in the morning around 8:30am and requested them to lift the car. Once lifted, the gap between the spring was adequate to slip in the buffers. I sprayed the WD-40 on the spring to lubricate them and inserted the buffers. It was bit tricky to insert the first end, but once its done, rest is piece of cake. I made sure to put all 4 buffers in the center of springs.
Once in place, I tied them with cable tie and ask the guy to slowly put the car back on ground and stop as the tire touched. Confirmed once again that all the buffer are in place and thats all.
1. Cornering was improved.
2. As far road clearance, at standing position and empty car, there was no change in the rear, however, the gap between front tires and body increased a bit. However, with passengers in the back seat, I noticed slight difference in the gap i.e. compression was less. Unfortunately I don't have any benchmark point in Islamabad (Speed braker, Ramp etc) where I can check the end result. In fact, my car hardly bumped any point in Islamabad and it was only in Lahore where I felt the need for spacers or better road clearance.