However, with high rates, the next mortgage would be very expensive, and a vacancy would be intensely expensive with two mortgages.

Small multi-family properties starting at over $1M, which is pretty expensive and, resale single family (before year 2000) offer minimal cash flow (~$200-300/month).2.

A high property tax rate will increase the taxes more quickly as a percentage of total expenses when the property value increases.

Denver is very expensive for a new guy who doesn't have loads of capital so a market like Missouri for example is intriguing for far cheaper real estate but then Id either have to move, improve the property remotely or simply buy and hold as a rental for X time. 

The problem is that your debt payments are going to basically wipe out that $400K profit unless there is room to increase revenue or reduce expenses.

List price: 445,000.DP: 89,000Closing: 8900Total Invest: 97,900Projected mortgage: 2500Rent: 1700 per unit, 3400 totalTaxes: 42Insur: 263CapEx: 100Repairs: 100Vacancy: 100Total expense: 3105Cash flow: 295, 3.1% - 6.0% CoC return. 

It scales up to 37% once you get to around $12k of income but the UBIT is calculated after the first $1000 is deducted along with expenses and depreciation again only on the same % the property is mortgaged.

I always recommend to make even a little passive income from a rental after all your expenses, lets be honest you put a lot of effort into this rehab so you should reap a little return.

A business bank account can be used to separate your business income and expenses from personal income.

There are less expensive hard money lenders out there.