My last rehab was projecting far better than a 2 to 1 return which was fortunate because we went way over budget (my worst over budget by far ever).

This is not personal, but if a person cannot save money now real estate is the worst investment to get into as it is one of the most cost intensive businesses to be in.  

You might also meet title agents who have resources on, say, foreclosures or probates…and might recommend lenders who actually lend on more difficult projects (as the title companies also know which lenders can close and which are difficult).I also go visit open houses to see what sorts of finish to put on my renovations or to look for the next house or area in which to purchase.  

Assuming you want to aim for syndication, you sort of need to learn how to develop a pro forma that ties the return to an IRR/XIRR. 

All fair questions and yes, there are far too many variables to say with any sort of certainty.

You have many options here.1) Terminate the lease: It clearly states that they must have renter's insurance and the lapse can result in a default2)Have them cover the damages with sufficient evidence that they caused it3) Claim it on your insurance for the property, likely they won't give a good payout unless a fire, flood, or some sort of wind damage.

I would look at it in terms of whether you can afford a worst case scenario where you're covering the deductible and have a credit line or cash to front the re-build cost and getting reimbursed from insurance afterwards.

And why 20-80, is that some magical ratio, or perhaps it's backed up by some sort of statistical analysis? 

I can tell you from experience one bedroom condos are among the worst long term real estate investment performers.

Over the past 24 months I've built two homes and renovated another, but I now realize I may have hurt my financial positioning by using all cash and not setting up some sort of LLC for these projects.