I am very surprised that there are people purchasing property before the US election, that could mean changes to taxation for instance. 

I would prioritize finding an accountant who specializes in real estate taxation over one that is local.There are 20+ accountants on this message board who specialize in real estate taxation.

Did you factor in quarterly pest control? 

Taxation for long-term rentals can be different than taxation for flips.You live in NYC - do they understand NY/NYC taxation. 

I personally do every quarter ( 90 days ).

I have a seasonal rental down by the beach, been winterizing it the last 8 years but 3 back a plumber didn't do a good job and busted my almost new furnace I'm toying with the idea of putting in 3 or 4 well-placed electric heaters in the walls which would cost me a quarter of a new furnace.

However rule changes in zoning (I think your lot along with all the others is RSL now)  that are fairly recent  may mean you can legally divide the home into at least 2,  maybe more completely separate living quarters.   

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.

I own a duplex right now on a double lot and the current buildings occupies about a little over a quarter of it.

It would appear he's advocating taxation on unrealized gains.