Input is 2 floors house, the first floor has cement floor, the second is covered with plywood.

But there are roofers that will work during the winter and you can put cement under a hood with a huge heater to cure it, but it isn't optimal.  

The crawl space is otherwise very clean and has a cement floor.

Glad she did.Anyway, I have used D&G Cement Company for a Redford rental.  

Also, there is the crack running across the floor of the garage so there is a possibility the cement may have shifted down lower allowing water in.

Professionals drill (two feet or the longest masonry bit available) into the hole every 24 inches around the exterior and interior (if the basement is not finished) perimeter of the building and spray the chemical into the hole.After you have sprayed the chemical in the hole patch the hole with cement so the rain doesn't flush the chemical out.

One property I was shown had obvious structural damage on the porch (the cement was buckled in and up).  

If its cement block it should be firm if bonded to the block.  

Finding her (actually sought her out) and talking with her cemented in my mind there are legal ways to accomplish wholesaling and some Title Agents like her know the correct ways as well as newest restrictions.  

That newer asphalt, or when it is resealed or newly striped, looks pretty sharp (but then you have some costs and maintenance), but I am not sure the attractive lot would bring much more in rent nor would gravel drive off good tenants.Finally, I shovel snow with the body sled type shovels and it would knock me out without a smooth surface underneath like asphalt or cement, so with gravel maybe check how that would work with your snow removal system (be it shovel, snowblower, or plow truck)...probably gravel best fit for plow truck...Best of luck