Hi,
Answers as follows:
1. The version of vCD is 1.5.
2. I think it's just a 1.5 feature which i'm accessing with 1.5 API version
3. Created the vApp in 1.5 UI itself and using 1.5 API
I have obtained other vApps in the same Org VDC and other Org VDCs as well.
Thanks