Type in New Delhi, India
Select the date of last entry and then type in the point of entry. The form does allow one to type in that field. If it does not allow you, then update your Adobe Reader and try again.
You can leave this blank. However, since you mentioned that your parents came to Canada earlier, it means they already have a UCI number. If you can locate it, it is well and good (should be on the visa printed on the ppt?). But there is no harm in leaving this field blank.
Evaluate your pros and cons. If your parents are tech-savvy, providing their details can help in certain circumstances. Most communications are done via email. You can provide your details too. If you do, ensure that you also fill up the Representative form with your contact details. This way, you would be able to may inquiries about your parent's file in future.
Most people fill their (sponsor's) information in these fields and also fill up the Representative form with their own details.
India does not have a "formal document" called "National Identity Document" As such, you can leave these fields blank. Providing details of Adhar, Election or PAN cards would not do any harm (will further prove identity of the applicant). If some dates are missing, just provide dummy dates and clarify this in your covering letter.
Wherever information is needed, you need to fill it in. The only time you would need handwritten text is on Signatures or names in regional language (this is not necessary). So, enter all information and only then validate. Validating and generating barcode IS MANDATORY. You can scan all filled-up forms and email it to your parents for their signatures (ensure you put sticky notes on each page that needs signatures/dates). On my mom's application, I had a scanned copy of her signature that I used on the forms (saves a lot of back and forth). Just make sure your parents know about all the information on the form and that they agree to it. CIC has a nasty habit of changing the forms. If you do not send in the latest forms, they simpy return the application back. So make sure you fill in the form at the very last possible moment (a week or two early is good enough - but not months in advance).