Maybe a steel plate used in road cunstruction could be buried a few inches and covered with gravel or dirt?

I agree with the others who say to re-nail the nail and add a screw about an inch above or below each popped nail.  

The space between buildings is only 16 inches, so I don't know how someone may be able to get there.  

New residential buildings that contain not more than two dwelling units shall have minimum 4 inch (102 mm) high numbers, with a minimum stroke width of 1/2 inch (13 mm), and shall be internally illuminated by means of a low voltage power source during the hours of darkness.

Every inch of the house is covered in it. 

It was required if you planned on doing a job larger then several square inches on a wall and on a building built before 1970's (forget which exact year), which looks like you are doing.

is there proper insulation in the attic of a minimum of 12-14 inches?

Regardless, depending on the police departments sophistication, they will examine everything inch of the unit before release it back to you/tenant.

(There was a battle between Condos in Irvine or SFR in CH)I'm in the process of renting this 4/3 2240sqft SFR out this month and I've read through most of the sticky* discussions on tenants and renting which helped a whole lot. 

Floor in lower level is settling or settled about 2.5 inches, it even feels hollow under.