This could be as high as 18%, per the statutory maximum from FSS 197.172(1) or, very often, as little as 0.25%.197.472    Redemption of tax certificates.(2) When a tax certificate is redeemed and the interest earned on the tax certificate is less than 5 percent of the face amount of the certificate, a mandatory minimum interest of an absolute 5 percent shall be levied upon the face value of the tax certificate. [...]Translation: When a property owner pays their delinquent taxes and thus redeems a tax lien certificate, if the certificate has yet to accrue a total of 5% at the rate at which the winning bidder won the certificate, then the winning bidder receives 5%.

I was fortunate as I worked in the largest Tax Lien Foreclosure law firm and processed many tax lien certificate foreclosures and got my feet wet as they say working other investors files. 

3) Nothing about process of how maintenance handled?

Due to item 1, adding an ADU can require years to start achieving any return (once the accumulated cash flow recovers the initial negative position).4) Adding an ADU is a slow process.

I'm considering self-management and I'm in the process of setting up systems for it.

it was obviously worth it to get the reduction, but it was an extremely frustrating process. 

Very straightforward process if you have the tenant in there and want a full cash-out refi.

For a 1000 unit SFR portfolio in Tampa, you could have a portfolio manager in Cleveland, OH, a call in Center in Topeka, Kansas, remote customer service team members in Mexico or (offshore) in India, and a rental payment processing center in New York.

Being incredibly new to this whole process, there were plenty of things we learned.

Hey BP family,In the process of putting in offers for a SFH, with a primary residence loan.