Is it typical for larger homes to  command a higher LTV(80-85%)  from cash buyers since the potential profit is larger dollar wise?

They typically have one or two inspectors which means your plan and your inspections can easily drag out. 

Does anyone know if this amount is typical.

Not a developer, but I think typically builders don’t want to have more than 25% of the finished product into the lot costs.....seems like your purchase price is too close to the individual lot values, after subdivision.

I typically figure 3% and I'm usually pretty close.With that being said though, I have heard of people buying a property and only making $100 a month cash flow, and I wouldn't waste my time on that deal either, because my liquidity is limited.   

They are typically big ticket items like furnace/ water heaters/ ac.

Also, in my experience, it's typically much easier to negotiate with another agent.

These people typically look for retirement housing that allows them to visit mom and dad in nearby care facilities, and they're also worried about aging in place themselves because they have firsthand experience with the problems of noncompliant housing.As far as I can tell, astonishingly, no one else is doing this in rentals in Pittsburgh, despite the obvious demographics. 

For example, if they have 30% equity for a $100k listing, your minimum offer will typically be $70k because that's what they need to pay the remainder of their loan.

Typically, can vary in markets, a vacant infill lot is worth about 1/4 to 1/3 of a newly built house.