You are required to close if the assignee doesn't.Saying attorneys are ignorant of the law is hubris in the extreme. 

No SEC requirements.

There are lenders out there that will lend up to 50% of the AV with no minimum credit score requirements. 

This reserve amount represents roughly 2–3 years of projected repair costs, which might be a conservative approach, but it gives us a buffer for unexpected, high cost repairs when they pop up.With a larger portfolio, the reserve pool wouldn’t need to grow proportionally, as funds and repairs can be balanced across properties, allowing costs to offset each other over time.

If they are, it will be expensive and / or require SIGNIFICANT equity.

Use the proceeds to pay off your high-interest HELOC, which will reduce interest costs and improve liquidity.Sell Underperforming Properties: Consider selling properties that don’t cash flow or require significant management.

The IRS typically requires the property to be placed in service as a rental property before you can start claiming depreciation.Once the property is converted to a rental and placed in service as such, you can then conduct the cost segregation study and claim depreciation on the rental portion of the property.

I have one and they're currently at 4%+, no minimum balance, no transfer fees and unlimited transfers, and they pay out interest monthly.

If the building is currently recognized as a single family residence,  then you are changing use and presumably will need to sprinkler the building and satisfy other fire rating and STC rating requirements not to mention the added costs of having to run mechanicals for multiple units, multiple kitchens, additional bathrooms etc.  

Assuming you paid $430k, put down 10% ($43k) so have a loan balance around $387k and $100k in equity means it’s worth $487k.