For example half an inch in Chicago like 20% of people clear their sidewalks and it just turns into slippery ice.  

Especially if things like roof, siding, sidewalks, parking lots, etc need replacing.  

Check to see if you have to install any manholes, fire hydrants, curb, gutter, sidewalks, street signs, street lighting any specific street design or access requirements, Check DOT requirements for access, stop lights and permits, traffic studies, DWQ requirements for permits, permit fees and time frames.Once you have an idea of what you can build and what is required in terms of permitting and infrastructure you want to talk to some civil engineers, architects and commercial general contractors that do the type of projects and build the type of buildings you want to build so you can get an idea of costs, time frame and requirements.

It’s a modern city with sidewalks, traffic and people and the only mountains are in the far distance.

Some likely issues could be:- is there lead (should get lead free cert)- is there asbestos- condition of roofs - past loss history- condition of the roads, sidewalks, drive ways, etc

Additionally, when I have placed open house signs out and the corner happened to be say a gas station, I went up to the window and asked that person if it was ok and got that ok since it would technically be on their property and not actually on a sidewalk.

For your first job, I definitely would not recommend this if you have zero construction experience.As for missing anything, have you accounted for flat work (driveway, sidewalks, ect), landscaping, fencing & appliances)?

Start with the end value of the buildings or lots and work backwards.Next check with the city or county to determine if you can do what you want to do and what is required for all zoning approvals and the time frame, Ask if you have to install curb, gutter, sidewalks, street signs, street lighting or any other special requirements.Are there any specific street design requirements, DOT requirements, permits or traffic studies.DWQ, Army Corp or any other environmental requirements or permits.General permit fees, proffers, water/sewer tap fees and the process of setting taps and connecting.

No lawn, just a small sidewalk out the front and back doors that the commercial tenants will be responsible for.

Here's a breakdown of local crime stats, on a per-neighborhood basis.One step you could take is to plug in the property address to the Alameda County Assessor's website and see if the city or county have recently levied any special assessments for things like street paving, sidewalk repair, etc.