From gross rentals, a license fee (to use a well known brand hotel), and a management fee are deducted before I would receive my net rental income, which would pay for the mortgage, taxes, insurance, and HOA costs. 

Bottom line: most people are not cut out for PM (I'm including existing PMCs in this), and most people don't make much money doing it.  

QuickBooks will allow you to do Mortgage Amortizations, keep track of property Information like land description, square feet, purchase date, type of house, whatever you want QuickBooks to tell you, YOU CAN CUSTOMIZE it to do it. 

I have an existing mortgage on the property. 2) How does one obtain financing for such a construction job? 

With 20% down, mortgage, HOA, etc would be sitting right around $2500-2700/month range.

Does your bank/ phone provider or any other bill waive a late fee if you dont pay mortgage on-time, you don not even bother to ask becuause they wont, this is the way your tenants need to see this .

I started researching ways to buy homes less traditionally, and different loan programs for elderly, since they do not qualify for a mortgage with their DTI.

More details:I've got the opportunity to buy a multifamily building for $850,000.Rents will be $9,300/mo first year, $10,500 second year (two units need to be finished)$100,000 buildout construction loan built into mortgageCommercial mortgage at 9% first year and 7.5% interest permanent loan, amortized for 20 years with a 5 year balloon.

One I need delayed financing on, and the other im looking to finance purchase amount plus rehab, then into a mortgage. 

But, it is definitely possible if you snag a property that you can't pass up on to utilize a Mortgage Broker who can generally get you set up with something based on your needs at the time.