A lot of lenders used to apply 35% for expenses, but in the last several years, the numbers for supplies, labor, utilities, taxes, etc… have increased significantly.Also take into account the age, occupancy and how has the property been maintained, this will affect the expenses too

For bookkeeping it depends on your portfolio.A portfolio of 1-3 SFR's can likely be a DIY project.For 4+ you may want to consider outsourcing.For tax prep, you'll likely want to have a pro handle it regardless of the portfolio size.

You may be able to deduct mortgage interest and property taxes before the property is in service. 

You do not need to provide tax returns, W2s, paystubs, etc.

However, the success of this approach hinges on consistent appreciation, which depends on demand.The Key Factors to ConsiderPrice Dynamics: Prices are driven by the balance between buyers and sellers.

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.

Could VRBO users from Michigan provide some clarity about the topic of sales tax/lodging tax collection and payment to the state.

I don't know the answers on taxes, but New Jersey is the densest state in America.

When I did my first house hack in Columbus I showed very low income on taxes. 

If you don’t owe then, everything is profit without paying overhead depending on the structure of your lease.