1. Put the name of the city where the Canadian embassy is located in India
2.If the places you have to type have turned blue and you cannot type in them, these questions do not apply to you. Leave them blank.
3. If you do not have a UCI, leave it blank.
4. Put your parents phone number(s) and email. If you want, you can fill out the "Use of a Representative" form (IMM5476E). This way you will be the one recieving all information about the progress of the application, not your parents. I did this for my mother in law's application. CIC would send me any mail or emails, then I would have to inform her what needed to be done.
5. Put in the information you have for the National Identity Document. Leave the issue and expiry dates blank if the document does not have them.
6. If you validate the document and want to change something, it is not a problem to validate it again.
My suggestion is to validate the document, print it out, and send it to your parents for their signatures. Or email it and have them print it out and sign.
Most of your questions are the same things I had to do for my mother in laws application, and we had no problems with it.