My plan is to build 2 smaller units (less than 1000 sq. ft. each), so designing ahead/purchasing plans online is feasible as the builds will be fairly simple - thanks for the tip. 

Roofs, HVAC, appliances/kitchen remodels, flooring, interior and exterior paint.  

Once the family members with disabilities or who are sixty-two (62) years of age or older, or any other family member, no longer reside(s) in the premises on a permanent basis, or the title is transferred, the property owner shall notify the zoning official in writing, and the accessory family dwelling unit shall no longer be permitted, unless there is a subsequent, valid application.As you can see, it's really all up to the zoning department of that city or town, and my guess is that if your proposed use doesn't meet the above, they will not approve it.It doesn't really sound like they're talking about an entirely separate structure, so if that's true then the question about getting bank financing for such construction would be moot, but it's possible I'm reading the above wrong.As far as whether you can build on the empty small lot in general, you'd want to look up the zone of the lot on the assessor page and then look up the Permitted Uses section of the Cranston zoning ordinance to see what can be built there and Zoning Districts Designated to see if your lot meets the minimum lot size to build something.

@Matthew WilliamsHi Matthew, I'll be looking for a property where I'll be doing a cosmetic rehab on it and at max I'll be upgrading the kitchen and bathroom; just to bring the property value up a little.

The main floor includes an open living/dining/kitchen area, two bedrooms, and a full bathroom.

Construction, design, development, etc).

Your reserves would cover that, barely, but then landscaping is not covered, appliance repairs, plumbing repairs, HVAC repairs, roofs, gutters, kitchen remodels, etc.  

Kitchen and bathrooms are the next important thing.

@Rob Shah to echo what @Mark Ainley said, there just aren't many areas where the buildings are designed to be rentals.

It's like watching Kitchen Nightmares with Gordon Ramsey.