Look up and understand the Rent stabilization ordinance (RSO) and what it applies to.

I don’t make money off of people applying.   

They still do reno work and the same rules apply.

If that applies. 

You should consult with a cpa for details how it applies to you.

And then there's no guarantee you'll even benefit from depreciation as IRC Sec 280A(c)(5) applies to a vanilla "house hack". 

Just as important as the Act itself is learning how the Residential Tenancies Tribunal (RTT) {formerly the Office of the Rentalsman} applies the law and the regulations which accompany the law.  

I am contemplating to using if this is good strategy.I am thinking of doing a refi 30years in an investment property and do a cash out and do a refi cash out on a Vacation property that was bought for cash and rehabbed and then apply a combined lumpsum payment to my primary home that I am paying a good amount in interest $1200 and there by increase equity and get a heloc open for use for the next coming investment.

Rules apply to all groups and classes.  

The repayment terms for a 401k participant loan are equal monthly/quarterly payments of principal and interest (typically prime plus 1%) over a 5 year term (longer if used to acquire your principal residence).Please note that if you take a full $50,000 and then pay back the loan, you can't take another $50,000 until 12 months after the first loan was fully paid back.Per the loan offset rules that went into effect with the 2018 Tax and Job Act: if you leave your job and the loan is current at the time you leave your job but then the loan goes into default because you left your job, you will have until your tax return deadline (including any timely filed extension) to make the loan current by depositing the outstanding balance into an IRA (and thereby avoid the taxes and penalties that would otherwise apply).Please keep in mind the multiple loan rules:Under those rules, the sum of the balances of a participant's outstanding 401k loans under a single 401k plan (using the highest outstanding balance of each loan over the last 12 months) can't exceed 50% or $50,000 whichever is less.