Answers from my point of view are below.
1. You can print the PDF template but this is to be handled to them for guidance purposes ONLY. The most re-type what's written in the PDF template and print it in an official University sheet, stamp it and sign it. If someone who is not the Dean of Grad Studies is signing the letter, this person most declare that they are a Dean's delegate.
2. They will only give you points for the primary NOC you state in your application. If you decide to include the NOC with 4 years of experience as the primary one, they will basically ignore your RA/TA letter. Make sure that letter you have with 4 years of experience is not a letter from when you were a grad student, because they may wonder why you were working full time while you were a grad student. Heads up!