So my question is, where can I find analysis tools or spreadsheets that I can use to work out the numbers and put together a formal/semi-official/convincing package to present to the prospective investors?  

If it is, I plan to invest a lot more.How did this work out for you?

Going into partnership solely because you’re friends usually doesn’t work out well.  

The only disadvantage would be that you would most likely not be able to get financing for this property, but if you have the cash to invest, it should work out very well for you. 

Work out a deal that way.

Paying me for wood and gutter work out of that money is actually paying me with my own money that I already had.

I am not expecting things to work out as you implied but prepare a good exit plan.

@Steven WestlakeThis seems like a management intensive business without much standard operating procedures already out there.

That's just a rule of thumb for a quick calculation.Flipping is could be cost intensive and then bring tax liability when done as a one off, for instance if you did 1 per year maybe it's not worth it. 

Get a written agreement from the neighbor that they'll allow it to stay but it must be moved onto your property if it is every replaced.Talk to the neighbor and see what you can work out.