Thanks a lot maxjj.
As you too are from Australia, more reasons to plan a visit there; Jumping kangaroo shots to be discussed over fosters
These shots were taken while working on March assignment and so no scope to zoom in beyond 50 mm FF ie 33mm on my D5000. But yes will try with more zoom for subject isolation for other photos.
The day was very sunny, in fact too much light at 2-00PM. People can be seen using umbrellas. ISO was on auto. You are very right that ISO should have been boosted or flash should have been used on the second shot too (now I better understand the advantages of direct access buttons

). Flash - rear-slow, was used for different reason for different photos:
Shot 1- The subjects were in shadow of the buildings and also sun tilting opposite to me. So used flash for this one. Subject not very far, so –ve compesation.
Shot 3- The faces were in shadow of a shade over head and without flash at 200 ISO was coming dark. Spot metering from face might have blown out too much of lighter objects.
Shot 4- I was at an angle of almost 45 degree to the fruit seller who was in shadow and as is visible from the 45 degree shadow near the girl's leg, the sun was almost on the lens. To counteract the sun into lens and to get the details of seller, flash was used. Since subject was comparatively near, so dialed in –ve compensation.
Regards,