The less you put down, the better your cash on cash.I would also look at what type of cap rate you are at and whether this property is trading near a market cap rate, since this is more operational in nature and not reliant on financing.IRR is also important, as it takes into account the time value of money, but there needs to be a capital event (sale or cash out refi) to make this equation work.

Most insurance companies figure homes that are over 100 years old will have more issues and equate to less money in their pockets.

The number of houses shouldn't even be part of the equation. 

Finding the buyer, tenant/buyer, or tenant is usually the easier side of the equation, assuming you market aggressively and your asking price/terms are in line with the local market.

The flipside of this equation is this:  every stock that you currently own is probably "on sale" right now and you could purchase a larger share of that company for the same price you paid earlier! 

>40% Equity<$75,000 loanI was quoted 3.0% 15 year, paying 2.125 points.Each point is worth 0.25%, or so I hear, so this equates to approximately 3.53% without points.I am being quoted 2.75%, 15 year on my primary residence, so that appears to be about a +0.75% spread between Primary Residence vs Investment Property.This seems consistent with what I have been reading online (0.5-1.0% spread is typical).Do you all agree?

Insert grenade into equation and you'll have a good understanding of how a deal can blow up, but it provided an opportunity.

Selecting a geographical area you think is promising is one part of the equation, the class of investments is another part, and arguably the most important is people.

This makes sense when you see yourself owning the property for awhile, the PMI payoff equates to about 3 years of PMI payments typically.

The personal side is half the equation on lending.