As long as your rental income at least covers the financing and cost of ownership, you're golden. 

Just about a year ago, I sold 2 of my homes in order to buy a 4-plex and very happy with that decision (mortgage/taxes covered by 2 of the rentals). 

@Lloyd Lau Assuming there are no structural issues and the 120K per unit covered electric and plumbing, would the deal be worth it?

You can check out the store, https://www.biggerpockets.com/store, which has books endorsed by BP that cover a wide range of topics. 

We are just speculating on the upward moving of this market because the house price keeps rising and there are organic factors that support it so in a moment we think negative cash flow can gradually be covered by picked up rising rental rate, but i guess its not financially sound on this deal

I had insurance on the property, so im covered in that aspect, because they are rebuilding my unit as part of a mass rebuild project jointly with the HOA insurance.

I feel like someone should do a video and walk through of a real life MLO contract, covering each section in detail

Creatively, you might find someone to partner with to cover rehab costs, if the property rehabbed will bring in more than you owe, the difference becomes the partner's profit.

The general idea is the bank will loan you extra money to cover the cost of repairs,  this is typically only done with commercial loans and they usually escrow the money and release it to you as you complete the repairsBy way of example say you buy a 500K house that need 100K in repairs. 

I had a rental appraisal done for it for additional cost during the process and the results were good enough so that 70% of that number covered my Principal, interest and insurance and property tax payments with a little left over.