OP, keep in mind not having access to heating and sharing same water heater and etc will require an easygoing tenant in the nextgen.

It is pretty easy to keep it fully occupied but it does mean I turn away a ton of people who want a lease that doesn't quite fit my requirements. 

I have seen many investors fail here because they only have 1 or 2 properties and when the downturns happen it kills them,  So you are going to need more money and more properties to balance out the ups and downs.Investing takes time, it doesn't happen overnight, and I think people fail to keep with it when it doesn't happen immediately.  

Keep detailed records of your hours and tasks—it’s crucial for proving active status if ever questioned.Don’t overthink starting with Airbnb/VRBO.

Is there enough parking for five vehicles?

Finally, even as the landlords cash flow increases, depreciation should keep a major portion tax deferred. 

Keep expanding, receive a larger line of credit (never come out of your own pocket), and scale to funding bigger deals where you can get your money+, and also equity in properties. 

It can help keep things straight, and it would look more legitimate to lenders, buyers, investors etc.

I have 2 options:- finance the construction pre-selling the apt, and take my profits (expected to be around 700K pre-tax); or- finance the construction with a 6-7%/year loan (collateral = my house), keep the 10 units, and once the building is completed in 24 months, rent them for circa 180K/ year gross.

I’ll keep your offer in mind as I evaluate opportunities and have questions about loan products or financing options.Thank you again for the support and encouragement.