It's not a problem with the concept of building a 2-4 unit property, the issue is all about the large capitalized expense costs vs. benefits.

It has to cash flow after all expenses or you're just buying someone else's money pit 

Specifically, they will be looking for capital for a down payment and operating expenses and reserves, capability to obtain financing in an amount sufficient to close the deal.  

I also write off the utility expense on my taxes.

But when it comes to starting a portfolio of rental properties, it gets really expensive to do so.

Rood and siding is in good condition, and the first major expense I see in the next five years would be replacing all windows. with a 15 year mortgage, at 5% (I'd rather budget high than low) cash flow would be 6056/year.

If you're seeing net $200 after all expenses then absolutely go for it.

Forming/ placing even a short wall is of course more expensive than a slab.  

They are homes in great shape but not real expensive ...anyone know of a lender that I can use to get this refi at a decent rate?

I did calculate 5% for vacancy and 5% for expenditures for unknown expenses.