For example, it the rate is 3%, but my investment only produces 5% return this is not a good use of the money (and if the return in taxed will be a net loss for higher income people). 

I'd weight other waterfront comps more heavily than non waterfront.

Surface- Rock or hard surface (concrete/asphalt); If on rock/asphalt put your tongue leg or stabilizer pads on wider pads to spread the weight out.

We went to see the Rolling Stones play, but the entire area our hotel was in had a loss of power. 

Any one thing has to cost more than anticipated to put you into a loss.

As with all the other investors with CALM INVESTMENTS was never compensated for any of my losses, which was every penny put in his Company.

It insures the Building, Contents, Loss or Rents, Detached structures, and Liability.  

He lives for 20 years - At 20 years it still wont be a loss maybe just not the best ROI.

Can you leverage the vacancy as a loss in value? 

Of course, anything can happen to anyone at any given time (health, job loss, etc), however, you have the highest chance of success with a Tenant who cares about their credit, and that is usually reflected in their score and report.