There are many statutory deadlines for notices and actions that need to filed, so I highly highly recommend engaging with an attorney, such as @Emmett R.

Question is how small is too small that would effect the future rental growth and property value?  

People need people to be happy and engaged.

It’s the effectiveness that makes the difference.

Think about it... its unfair for them because 1) They don't know the deal risk profiles nor the operators, 2) They don't know your future deployment plans to account for your estimated Adjusted Gross Income (effective tax rate) for the next few years, and 3) they don't know how much depreciation is going from the plethora of investments you look to go into.

I guess that I'm impressed they not only built out a model that could get with in 7% of FMV for that many homes, had an effective UX that made ppl want to use it, got a system up and running to take possession and make ready for sale that number of homes across such a geographically diverse area during a global pandemic which changed the way ppl work and lead to crazy home prices.

The lien should not effect the mortgage rate but the lender will more then likely require it to be paid off prior to or at closing and get a lien release that can be filed along wit the mortgage.  

The other thing is that your equity in your home always becomes less valuable/effective over time.

If it's truly valued at $400k, you could pull out up to $300k with no tax implications whatsoever (you'd be taking on debt, not incurring a capital gain).With regards to depreciation, engage a great CPA who understand and specializes in real estate investing, and ask them if it's possible to use a cost segregation study to take accelerated depreciation.

A good tenant is someone who:Has stable employment in a market segment that is very likely to be stable or improve over timeHas a credit history with which you can evaluate the likelihood that they will performPays all the rent on scheduleTakes care of the propertyDoes not cause problems with neighborsDoes not engage in illegal activities while on the propertyStays for many yearsThe right tenant pool is so important that I would interview multiple local property managers to validate the tenant pool selection.