We determined the ARV, estimated our rehab, decided on our required profit, and then negotiated on the purchase price based on that data.

If you're going to make a lot of changes, I recommend consulting an attorney to ensure you're updated on the laws.

There's no true data source that aggregate all the data that you look for (at least to my knowledge).

He is unlikely to fight back in court when everyone in the house is against him.When he is served notice, ensure everyone is in the home to witness it and present a unified front.

* What do you do to ensure that the tenant is responsible for security deposit disputes since that is the largest reason for owner lawsuits* How familiar are you with the newly changed laws that can affect you the owner if they are not used correctly?

Those details can ensure your projected $25K profit stays on track. 

@Joe Gettler, I don't have great data b/c she just helped them for a couple of months, but I think it's just under $4K a month for a nice 2 bedroom in a good location.

Quote from @Scott Tennell: For real estate investors who have worked with private money lenders, what strategies have you found most effective in structuring deals to ensure both parties are protected and the funding process runs smoothly? 

Just ensure you do thorough market analysis to avoid pitfalls.3.

This approach allows you to have a legal presence in the country, which is often necessary for investing there if you don’t live in Spain.Having a virtual office in Spain through your LLC could help you access local tax benefits and deductions, such as expenses for mortgage interest, repairs, and insurance, which non-residents typically cannot claim.It’s worth consulting with a tax or legal advisor familiar with both the US and Spanish systems to ensure compliance and take full advantage of this option.