And maybe pay off debt first if those percentages were reversed. 

That's purely an investor only, no equity stake.Offer a lesser percentage, but a percentage equity stake on any refinance or sale on the back end.Go 50/50 partnership and they bring the cash you bring the deal.

The single best point buy I saw was a 1/4 percentage point rate decrease for a full point. 

Should the adjustment be based on any index or be a fixed number/percentage?

If I decide to buy a property in Maryland, does anyone know of any areas with a high percentage of renters ?

Yes the lender could call the note cause you transferred the property, but that is a very small percentage possibility.  

I know there are a lot of lenders who charge only a flat fee/origination percentage basically to keep their lights on but everything else comes from the title company. 

Whenever I buy a note (usually non-performing) it has to have plenty of equity on the loan to value as well as a percentage of loan balance.

As for refinancing, a good rule of thumb is that if you can get a whole percentage point lower, go ahead and save yourself the money, but for anything less than that, what you save in interest may be outweighed by what you pay in loan fees. 

One method used is a percentage of construction costs this percentage tends to range from around 4% all the way up to 15+% with the scale of the project inversely effecting the percentage used (bigger projects = lower percentage) after that baseline is established most folks will look back at how long it usually takes to do these projects as well as the client relationship and will adjust accordingly to reconcile these figures.