You will need a hard copy of the PCC (or a scanned copy if applying online). So, you will require the actual PCC. Only having the PCC application number doesn't suffice.
Once you have the PCC, you can apply online from India, sure.
But wait, this becomes a bit complicated. You must mention in the physical presence calculator that you are not in Canada, and haven't returned yet.
Not sure, looks like you can't apply before returning to Canada. Hope that clears your doubts.