Other software also has bank feed integration, automated income tracking, receipt scanner, accountant-approved reporting, etc.Of course, it totally depends on what features you prioritize! 

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.

That might include things like adding units, converting commercial space to residential, or finding ways to boost income (like adding parking).The key is recognizing opportunities while walking the property, and that takes experience.

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. 

At that time, my friend encouraged me to get into real estate with the idea of creating passive income and wealth in future (via appreciation).

This will allow you to qualify solely based on the income that is produced from the rent of the property.

I'm going to reiterate what's already been mentioned above, but I'm going to actually give you examples of why it's relevant to you to find a U.S. tax professional.1 - You're going to need to file U.S. taxes once you have property down here, there's federal filings, state filings, and sometimes local filings too2 - Tons of tax treaties between the U.S. and Canada that are easy to miss and can cost you a lot of money (important one with rentals - effectively connected income - if the professional you talk to doesn't know what this is, run away)3 - The amount of days you spend in the U.S. needs to be tracked and if you go over a threshold, all of your worldwide income could be taxable by the U.S.4 - Selling real property means up to 15% of your sales proceeds might not be available to you for years (FIRPTA)5 - Lots of nuance at the state and local levels, which both want to take as much money from you as possibleMain takeaway here is that you should find a U.S. based tax person.

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. 

They mentioned they didn’t need any income.

If you don't care about income and are more of a capital gain kind of guy, prices are already high (as you noticed) and there's plenty of land available to buy so I'm not sure how much is left in the tank.