My role is to purchase the property through conventional finance and to provide the down payment. 

Choosing to go FHA vs Conventional is more important than most think.

Freddy/Fannie conventional loans want to see those 2 years.

A pro forma puts cash flow at about $200/month for the building, but, since we house hacked, we just absorbed that into our regular spending with some regular savings for repairs and maintenance, etc.Come around to 2020, we (with our tenants help) have paid down 10 years on our 30-year conventional loan, held by Chase.

Once they have this information, they can discuss the options that they have for you - FHA, Conventional with 20%+, conventional with less than 20%, grants, etc.The main things you'll want to know are:- What loan programs do you offer?

I talked to a bank for conventional loan and either A: they require 25% down - which might work but prefer keeping a little cash for future deals or B: if it’s over 4 units he suggested to go with a commercial loan.Any experience?

@Jordan Pratt  Keep in mind that unfortunately for conventional lending, the down payment can't be borrowed. 

This doesn't take into account the time value of money, but as long as the interest rate is greater than the inflation rate, the net effect is that they're earning more from your offer than from another offer which is financed by a conventional loan. 

I know lot of people are doing this to get low interest rates with conventional 30 year fixed with only 20% down or less.

I do not qualify for a conventional or FHA loan because a year ago I became self employed so the best interest rate I can find is around 7% putting around $10,000 down payment.