I will change the assumptions and right away can tell it looks much less enticing.Property management to 10% Repairs to 5%CapEx to 10%Vacancy to 8.3% approx 1 month per yearAdded flat 150 per month for water but I wonder If I can charge 50 a month flat fee to Tennants or some average of years prior.With that I am now looking at losing about 250 a month on the deal.

I budget about 10% vacancy as well, but reserve about 1% of home value per annum in capex acros the board.Building a nice excel sheet with all these assumptions in for quick churning of comparisons is a good idea.

I see on YouTube, people talking about leasing other peoples properties on airbnb and assume that's not possible because why would someone allow someone else to lease their property when they can lease their own property out to someone and reap the financial benefit and also I'm going to assume that HOAs can block people from doing that.Am I correct in my assumption?

Banks rarely allow 100% financing on an assumption.

You will need to get your own casualty insurance.You cannot make decisions based on an assumption you will close in 30 days on a new loan.

Once that property is stabilized and performing to your expectation, continue on to the next property.My recommendation is under the assumption you have the ability to acquire traditional financing (stable employment the last 2 years, have funds available for closing cost, good credit, and have a decent debt to income ratio). 

I utilized the same cost assumptions that Brandon Turner utilized when he demonstrated the tool on the "How to Make 2020 Your Best Year in Real Estate" webinar.  

Speak to you PM to confirm your underwriting assumptions to sharpen your numbers.

I'm much more interested in getting my erroneous assumptions corrected, and learning where I'm missing the mark. 

Would I just send the buyer an Assignment of Contract with all the terms that he and I agreed to, and have him pay me a flat fee up-front or maybe when the assumption process is complete?