The problem I see right off the bat is that in the US, a house in this condition cannot be lived in. One would assume that there are similar laws in Canada. Even the ad says that it's been boarded up per city order - that usually means you cannot live in it. Until you repair it to the point that you can get the city to allow you to live in it, you'll still be paying rent. Even worse, many mortgage companies will not give a regular loan to houses that can inhabitable. You have to get a higher interest 'construction' type loan. The house is not "huge". It's 1540sqft. To turn it into a duplex, you would need to follow the building codes and divide it. You would also need to add a kitchen, which is going to incredibly costly. You also need to take into account property taxes and increased living expenses. Heat, electricity, and water will likely cost more than at your old place. If you want to do it, be sure to get a FULL inspection on it to see what it actually needs. Then, you can price out the cost to fixit and see if you make enough to do it in a timely fashion.
Unless you've taken on a project of this magnitude before or participated in a project of this size before, you can't begin to estimate just how much work and how much it will cost. For starters, you're going to have to get a furnace installed before it'll even be warm enough to work on it. When I had a mid-efficiency furnace put in it cost over $15,000. And that would be just step one, and not something you can likely do yourself. Can you really afford this on top of a mortgage? The place is boarded up because it's condemned - so you wouldn't even be able to live there for about a year as you get the floors put back in, running water, electricity, etc. So you're not saving any money on rent for a long time to come. I'd run the idea past your carpenter and electrician friend too. While people generally want to help their friends out, you'd be asking for months of labour from them which wouldn't be fair to expect them to take a significant pay cut for their services or work for free, so you won't be saving as much as you'd think. Calling it a "Handyman's special" is an exaggeration - this is a "Builder's Special". Find something that needs minor repairs and you'll have your hands full enough, but this is not a good first project for anyone who hasn't already participated in a complete gut and rebuild before.