The SFH is in Irondequoit NY and it seems that the Sewer line is partially blocked.

I sort of dismissed this path thinking it was perhaps along the line of a "loan shark" or a payday advance. 

All units 1 bed/1 bath.

Or just to keep in original format with 4 beds and 1 bath.

What about the trend line here in red?

Very true @Dennis Mears, the market could support probably 250$ more based on my research (only 2, 2 bed houses for rent in the whole city, and they are going for 200$ more than my proposed $150 more price.) but vacancies are expensive and having them been there 3 years they must be decent, just some bad habits from previous landlords 

As an aside, could it be subdivided where each property would meet current setbacks from front/rear/side lot lines?

A lot of the other numbers they provided seemed a bit out of line from what I would typically expect too, the water testing I’m not familiar with and though I may get some good guidance as to whether the costs seem right or not.

I once did a contract for decent sized order of a about 50+ line items...

., XL backyard, koi pond, very well landscaped. 6 beds, 4.5 baths.