Hey buddy, I wish I could answer your question. I am not a 100% sure, but I were you, YES I would use the #2 courier address. And I also think giving your work address as return address should be perfectly fine.
In my situation - The address CIC had on file was my consultant's address. I emailed them my home address in US, but never got a response back. So I assume they dont respond to address change emails. I made the mistake of enclosing a UPS shipping return label (next day air!!!) but then realized its just a waste. CIC has sent my passport and docs on Mar 6th by regular mail but i still havent received them. Not sure if it is stuck somewhere in customs.
Now looking back, based on my experience, I think my best advice would be -----> do you have any relatives or friends or your consultant in Canada? if yes, use the Xpress envelope and have your passport shipped to them. THen ask your friend to over night it to your office address. Just my 2 cents.