I have heard from numerous sources that instead of mailing the required OSAP documents to the Financial Aid Office, we can simply scan the documents and send them in .PDF format, is that true?

I have never heard of this. I've done OSAP for at least 3 years now and I never hand in the signature pages online. I always mail them...

Yes, I have done that to my OSAP signature papers as well as my Canadian Immigration documents and they were both accepted!