Canada

Valuable in what sense? Do you wish to pursue Masters and you mean is the degree recognized? Or you are asking about the job market? Please explain further.

Yes, diploma courses are really popular courses among Indian students going to Canada. They are a lot cheaper than Degrees and serve the same purpose.

They are both very well respected universities and the tuition fee is below 10 lakhs at both the places. you can also consider University of Saskatchewan for the same course as well.

Universities abroad don't look at only your academic scores. They look at your overall profile. So if you have a good subject understanding, and have a well-rounded profile you shouldn't have any issues with admission.

It is mandatory for embassy attestation. Apply immeditely for duplicate certificate in prescribed application form and pay the fees prescribed in the form of Challan /DD.
You need advertise in news papers the content how you lost it, with register number and also want to get principals signature.
After completing these, approach a Notary and prepare an affidavit. These are the procedures.

Yes you can. here is the link to best universities and their requirement. you may choose the co- op route or the direct one and apply.
http://www.canadianbusiness.com/lists-and-rankings/best-mba-programs/2016-reputation-ranking/
All the best

Dear Rajan,
There is no official ranking system followed by Canadian universities. Among the top most you have McGill, University of Toronto, University of British Columbia, University of Waterloo and Queens University.