If you spend a few bucks on landscaping, lighting, and other exterior/neighborhood-type improvements for each of the buildings, you'll raise the desirability of the area at least a bit.

My estimates include modest landscaping refreshes and often $10,000 in plumbing/electric, properly refinishing older tubs and sinks, not replacing with fiberglass, proper renovation of wood siding, not covering in vinyl, etc. 

This can cause additional expansion and contraction of the siding and warping of the metal.

Because I am not supported financially by the organization I am associated with, I am working remotely part-time for my friend  as the Operations Specialist for his window repair company based out of Lakewood, CO, which means that I play a key role in most of the special projects, including innovation and expansion.  

Currently working for my township as a road crew worker also I have a landscaping business so I'm a very hands on guy.

Right now I'm mostly doing landscaping a few days a week.

Daria,lived in NJ all my life, things change everywhere, even my small town has some apartment complexes being built, changing the landscape of the town. yes i mean the downspouts, they should be put into a pipe and diverted away from the structure. that looks like concrete, especially the way it has cracked and i would guess the water is part of the problem, i think as you had mentioned, that it just wasn't done right in the beginning, i would call a mason, he would have to break that out, then make sure they put back at least 4" of stone and 4" of concrete with the 6" x 6" wire in the concrete ( this comes in rolls or sheets, the mason should know to use that. my guess is the room is 12' x 16' ?

The neighborhood is a C on an A-D scale - poor, but not especially crime ridden.Asking cost: $69,000 (let's assume for now I cannot get them to budge on price)Initial Investment: $17,475 (25%)Rental income: $15,600 annual ($650 per month per unit)Assumed Annual Costs: $12,07610% vacancy - $1560$1900 Property Taxes (estimated increase from previous year's actual)$900 Insurance (this is really a guess)$1000 annual snow removal and "landscaping" (no yard)5% repairs budget and 10% capex - $2808$720 water bill (estimated)$3188 mortgage (30 years @ 4.5%)Cash Flow: $3,524RoI: 20%CAP Rate: 10%Can you see any obvious errors in my planning?

With this being an REO the seller (bank) went with our cash offer).Improvement Costs: $2,100 (re screen porch, Landscaping (bad shape), painted entire inside, drained & filled 10' x 8' deep pond, Appliances) For a newbie, this house did not require much work which is not typical for houses in this price range in my area.

Regarding maintenance, a few things to check up on and improve: landscaping, exterior lighting, roof, HVAC, parking lot (specifically potholes and restriping), signage, interior common areas.As far as tenanting, easiest (and free) would be Craigslist.