Leaks can be easy to fix or very costly to fix.  

I'm in a different market and have a gas power boiler for baseboard heating. 

All that does is cost you more money. 

I'm afraid skylights might leak or increase the cost. 

Can try to reposition to Class B, but neighborhood may impede these efforts.Vacancy Est: Historically 10%, but 15-20% should be used to also cover tenant nonpayment, eviction costs & damages.Tenant Pool: majority will have FICO scores of 560-620, many blemishes, but should have no evictions in last 2 years.

You simply add up the “net sale price” (after removing selling COSTS, the mortgage isn’t a cost.) that how much you have to buy to avoid paying any taxes.

Cash-on-cash returns are what remain after vacancy costs, mortgage, and expenses.

We have substantial closing costs on the sale, primarily transfer tax and realtors' commissions.

Down payments are still standard for FHA or conventional (3.5% of the total cost, purchase+construction) and rates are on par with standard FHA rates. 

@Steve Boss,  Here's a BP blog we wrote recently on costs nationwide - https://www.biggerpockets.com/blog/how-much-does-a-1031-exchange-cost.Just because an exchange is cheap doesn't make it bad.