Do you have any experience with any of those strategies? 

Rates have come down a bit and can work in certain situations - but this one looks like it potentially has the factors to make DSCR work in this environment (lower on the value range, multi-unit, creative leasing strategies i.e.

He wonders: if my strategy is a solid one, then why wouldn’t everyone then just buy a home and then take out a HELOC against it rather than using their funds to buy the properties they want.

Multifamily in the US as a Canadian I would say is a sophisticated strategy, but it depends on what size you are looking at. 

I am looking to invest in a multi family property with a strategy of possibly house hacking in the miami area for around 500,000k price range

Now I've moved from that property as well and the next one will be the same strategy.

The HELOC is going to be your best bet.

but that's also a gift action as I vaguely remember.For the investment, you need control of the property, with ownership on her death.Your sales strategies will only trigger a sales.Is there any wiggle room on taxes?  

My opinion is retail (MLS), non value add buy n hold in this market is a long term strategy. 

There are numerous advantages to this strategy:-Learn the basics of managing a tenant and property.