According to the National Association of Realtors (NAR) the average flip makes $65k gross profit (before subtracting rehab costs, holding costs, etc) ,but only $15k net profit, (that's what you put to your pocket for all your risk and effort) and takes 6 months from purchase to selling.

I would subtract how much curb appeal would be needed from the price the owner gave. 

You will then add this profit to your other income, subtract out your exemptions and deductions and tax credits before figuring out your taxes.  

You pay UBIT on the income that is derived from the financed portion of the property after you subtract the percentage of all the expenses. 5.

The step up basis is they subtract the sale price of $3 million and $1.5 million so proceeds are $1.5 million and they pay capital gains tax on that amount.

To answer your question you need to determine the ARV and subtract all your renovation costs, all closing costs, carrying costs, etc.

Setup cost $1k/month, + lease $3k/month, plus insurance $1,250/month, plus utilities $350/month, plus maintenance $150/month, etc, = $5,750 expected outflow/monthThen take expected income $7,500, subtract expected outflow of $5,750 = $1,750/month expected incomMultiply $1,750 times lease months (36) to get gross expected profit ($63,000) and subtract setup cost to get net expected profit ($63k-$36k) = $27k To get total ROI multiply monthly expected expenses by lease term, add setup cost, then divide  gross expected profit by the result (($5,750*36)+$36k) = $243,000 ROI $63000/$243,000 = ~26% or ~9%/year. 

You expect to owe at least $1,000 in tax for 2019, after subtracting your withholding and refundable credits. 2.

This property has appreciated $4.3K/month ($3.4k/month when subtracting out $60K value add costs) over the hold period.Was it speculation? 

To determine NOI you will take the gross income and subtract ALL expenses to include taxes and insurance, property management, utilities, etc.