If you have a property you feel is distressed, then dive deep into the local courthouse records to learn more (assuming that's public info in Montreal), then go out to the place yourself.

The situation is that I own a commercial retail building. 

We currently own a 4bdr house, about 370k left in mortgage, retail value ~580-600k, monthly mortgage ~2600 per monthWe would be gone for 2 to 3 years.

Vinicius,Hi, best place to find local like-minded Investors is the local Investors Club. 

I took my knowledge andstarted working with local private people to fund fix & flip'sthrough the use of notes & mortgages.

If yes, and if you do not have much experience yourself, I would engage a local civil engineer to guide you through the initial planning phases even before you get to design & construction. 

I need to keep everything very local for now, which is challenging, but I'm willing to face a challenge.

STR's are a different beast entirely, whether professionally managed or not, but they do allow for an easier/quicker exit than traditional commercial such as retail, office, warehouse, or multi-family.

If it's feasible I always recommend to start investing locally and sourcing the deals, contractors and if interested manage yourself.

As far as getting best rents, I've seen professional photos make a huge difference and depending on your local market placing it all the typical property sites like Zillow, Trulia, etc.