Hi
I have not made the process yet but I can give you some tips, since you are in Monterrey the best you could do is to grab an utility bill (electricity, water or gas from your apartment) as a proof of residence and go the FGR regional offices. As for the Tourist visa, I suggest to explain the issue to the agents and they will sure understand that you do not have a "Forma Migratoria" since you left that status before and you are currently on a tourist status. You will need:
- the passport
- the utility bill
- the letter from Canada embassy
- any migration documents you have (FM3)
- your birth certificate translated in spanish
- the photographs
- the payment for the service
The "cartilla militar" does not apply to you . If they deny you the service then look for Agents ("Gestores") to do it for you.
One question, did you receive the PPC request letter from IRCC, before or after your AOR (acknowledgement of receipt)?
Regards