I intend to househack or STR, but with my friend who will be my 50/50 partner.

Your house looks very clean and new, but lacking a little character with no artwork. 

How well would someone accustomed to living in a dilapidated house maintain it during the sales process?  

More than happy to connect with you and talk about house hacking / real estate investing strategies.

For example, lets say I strip a house down to the studs and take of the siding. 

That should be your focus.Personally if you have one mortgage already that is negative cashflow I would be hesitant to buy rright now, especially in canada where from reports their housing situation for pricing is far worse than the US on affordability and just like US, people think prices can only go in one direction but reality is they are moving in the opposite direction.

If you have 30 houses with a total of $3 million in equity, then you could split them into three separate LLCs with $1 million each.The more complicated you make it, the harder it is to keep straight and the more expensive it becomes.

My plan was to build and sell the beach house or have it on AirBnB. 

I would house hack subsidize my mortgage which gives time to build up capital and would refinance to conventional loan and start my next investment!

I have a house there too near Stuart Patterson Park.