I assume the only way they wouldn’t laugh is because you are overpaying for the property and they are considering that overpayment additional interest. 

Understanding the different policies and your risk exposure is properly the most important thing to understand.Understand your deductibles and what is covered with your specific policy (i.e, is sewer back up included, flooding)You can always get an umbrella policy if you want some additional insurance.

Any reduction in debt or cash received may be treated as taxable boot, resulting in potential tax liabilities.

In addition to that, I check for criminal background and evictions through the local source for that region.

Otherwise, she will stay.You're charging her 25% under the low end of market rent and she's asking for an additional discount.

Additionally, commercial properties, such as office buildings or retail spaces, may provide attractive depreciation schedules and potentially higher rental income.

Buy something that the numbers will work as a rental and increase after some initial rehab during the first 1-2 years of having it as a primary, build additional savings and equity over time, and ultimately rinse and repeat/build a portfolio! 

Now they added 2 additional security.

Conventional financing, buying with cash then refinancing after rehab, partnering if needed, heck even using hard money might be preferable here rather than taking on the additional risk of using subto, without much benefit because of that high rate... 

It is always wise to have some additional capital on the sidelines to help advance your projects rather than relying solely on the bank draws but one month is beyond reasonable.