For a Gas-Station with total development cost of ~$1.5M, I will tell you our fees would be nowhere near 33% of that. 

.#8 I would consider your inspection cost a very cheap crash course in buying long distance investment properties. 

There is extra costs, more regulation, and more liability. 

What I do for my units with shared meters is I charge 50% flat to each tenant which prevents waste I get no issues with any waste due to this but the ones that share electric bills do get many complaints due to the size of the bill.

Are they flat fees or percentages? 

You are correct, that this has long been the conventional figure used to estimate cost for buildable sf in NYC. 

They city required that I replace the best sidewalks in the neighborhood under the program and the cost was substantially higher than estimates I obtained on my own. 

The rent difference versus the offset of cost needs to be calculated. 

If something happens to affect the cost you might be able to change the scope of work or timeline to compensate for that.   

Then a nice flat lot.