By you getting higher monthly "credits", will increase your ROI but will also, of course, help you cover all of your expenses, assuming that you have a pre-determined purchasing price in X amount of year that the tenants will buy from you. 

In most construction Basically what I am asking is Does the #, size and total amount of opening space per square foot in regards to windows on houses accumulate to a pre determined number or is it based on every house specifically designed with window location and variation in mind.How do they figure out how many windows and what sizes?

When I see figures like that, I suspect that the Report has been rigged by someone using pre-determined desired outcomes, rather than cold hard correct analysis. 

Searching for confirmation of pre-determined biases. 

I would say my biggest advice is use this time as a pre-determined study  / saving along with screening potential markets you might move to.

If you are trying to get a HELOC on a house you recently took a loan out on, then the bank may require you to service the loan for a predetermined amount of time before considering a refi or line of credit.

TLDR: What agreement should I write between my grandmother and I so I can take over her house (mortgage payment, agree to buy the house at a predetermined cost), while we keep in her name and then finance/buy it at a later time?

Often times we get emotionally over-optimistic about a particular property and we lose sight of the potential downside.I'm not sure if youve ever heard of a Monte Carlo simulation, but what that does is take your projected numbers and runs them through a predetermined number of simulations, sometimes over 1 million different scenarios if you wanted it to.

.- Our lease includes a "Purchase Option" clause, which when the tenant signs states that if they meet the conditions of our 4 year program they can purchase the property at the pre-determined price.

This would have to meet predetermined criteria that you set though, because you don't want them to send you everything under the sun that is a crap deal.