The interest rates are most likely a lot higher.

This includes rental income, which is typically taxed at a flat rate of 30% unless you elect to treat the income as "effectively connected" to a U.S. trade or business, which allows for graduated tax rates and deductions. 

For a $100k house, we can agree on payment terms and pay the seller $120k over time.

I sold one property just before interest rates went up, which worked out well for the sale price.

The next step would be to begin talking with lenders near you and see what kind of lending terms and rates you are able to qualify for.

Hello,I am remodeling my multi family house (3 flats) to modern.

Not sure where your property is exactly, but we find MTR rates are 50-100% higher than LTR rates. 

I constantly hear people online (Social media) talking about getting an FHA loan and house hacking a 1-4 Unit property.

The house is 1,800 sqft.When it comes to a cigarette smoke-filled home, combined with the need for a rewire, I am assuming the correct answer is to perform a full gut, right?

We manage several there that get a great rent rate.