Master Lease Option Questions

[Michael Strobel]

I've recently read and heard a lot about Master Lease Options as a way to take control of properties without exchanging title (at least initially). Theres a duplex Im looking at that is pretty bad shape but its in a good area. It is currently completely vacant (and has been for probably well over 2 years) due to the disrepair the owner has let it fall into. The owner knows it would be impossible to get a mortgage on it right now so he's been open to the idea of creative financing. If I can negotiate a cheap monthly payment to him and I can have the option to buy at any point within the then I can use private money/hard money for the repairs then rent out both sides for 5-6 years to at a significant cashflow in order to pay down the rehab and have enough cash flow for the option purchase price. Ive read Brandon Turners experience with his apt building and Ive done some other research but there are a few questions I have about it:

1. A seller (lessor) doesnt need to own this free and clear like seller financing typically is right?

2. If a seller (lessor) does still have mortgage payments, if we enter into a MLO and I start paying him/her monthly payments, what is to prevent him from not paying his mortgage and still getting my money? Ill never know if they paying his/her mortgage but still taking my money every month. Esp if the property needs significant amount of work, the last thing I want to do is put money into fixing it just to either have him/her default and Im completely screwed. 

3.If anyone has done a MLO, what were the pain points you experienced? How would you have done It differently?

Thanks!