The gate is tall, and metal but was here previously so has no way to close it. 

@Kim Hopkins Is the structure an actual metal building, or is it block and bar joist?

Brick chimney, metal firebox and flue.

I am building a tiny home that is 28' x 10' with 3 degrees of angle. I am trying to figure out if the dimensions the guy at the roofing company gave me are correct (I have attached them here). I would like 6 inches of...

If you discover a leak, quickly notify your gas company, they will help you isolate your line.Spray paint for metal/steel applications, id recommend a primer, and 2 top coats.

They seem to break in the very cold of winter or hot of summer because temperature puts more strain on the metal.

During the 3 encouters before choosing them I was told there was only a family 5 and I met all 5.

It looks dingy and needs to be "Turned".If it were mine, I'd do the turn and 100% repair everything, such as the back door allowing light through at the edges, the squeaking floor, etc... and there is not much kitchen counter space....Class-C's like to cook at home....perhaps extend the counter over to the stove, and maybe put in a bigger fridge, and a bright daylighter bulb in the kitchen.Also the living room floor looks wavy...I'd have that fixed, and remove the big brown shelf or put it in the laundry room over where the appliances go and paint it the color of the walls (but vinyl coated metal mesh shelving works better up there in a rental).That plus some (light) grey paint and "Properly installed" (non wavy) carpet.And look for Forever renter types...for a 1 br/1 (spacious) bath.Know your demographic, and know what they want.

The house has ducts for a heater but does not have a condenser and coil.

Foundation itself being isolated by the metal rounded piece is a good sign, so grading may not be the issue, but drainage water from downspouts or other features may be.