Both are for tracking income/expense and generate reports (P&L, cash flow, but not balance sheet) only, not for listing, screening, collecting rent. 

My markup is always lower than the original lender's because I don't spend money advertising during the Super Bowl, my president doesn't have a corporate jet, and we don't have layers of management we need to pay.

Velocity banking works by taking a huge 'chunk' and putting it down on principal, then paying down the HELOC with every penny of income you get. 

They generally treat the debt like they would with a rental and count around 75% of the gross mortgage payment as "income" in the DTI calculation.

If you are sole member LLC you just take a distribution from your business account to your personal account.You are likely already reporting the income on a schedule E.

FHA now allows us to count rental income from an ADU (additional dwelling unit) to help borrowers qualify.

So, when Trump changes to no tax on tips I feel inclined to change my rental income structure.50% reduction in rent.Previous 50% made up from a mandatory nontaxable tip. 

On a commercial asset the value is directly based on the NOI (net operating income).

Meet with a local banker & schedule a time to talk with a mortgage broker, they'll give you at least a baseline of what kind of down payment options and rates are out there.After that, if you're still wanting to research more creative options, do some looking into seller financing (a very hot topic with good, and bad, advice out there), look into private lenders, and commercial financing options.If you're wanting to live in 1/4 of your quadplex, then conventional residential loans may in fact be your best option as you can purchase that with a fannie/freddy loan with very low down, and use up to 75% of the income from the property toward your own income. 

Use tools like AirDNA or Mashvisor to provide market data on projected rental income and occupancy rates, and make sure your lender works with appraisers familiar with short-term rentals.