My template is gavick pro boutique. You're right I tried another template and it seems to show the 'not available' image, however there is still a problem with it as I thought it would replace the 'add to cart' button which is doesn't. People can still click on this 'add to cart' button and put the product into the cart. This confuses people and me. Ideally the 'not available' image should replace the 'add to cart' button, so I presume it is a design fault or a bug.
Also the 'notify me' does not work properly, it still places the product into the cart with zero values when you click on it. It doesn't send an email to notify the administrator like what VM1+ does.
As for the stock control problems you are getting, I don't seem to be having this issue. When I add 0 stock in a product, it tells me there is no stock available, so I assume this is correct.
To be honest without proper explanation of this, I do not know what is wrong or what is right, I just use my logic to work it out and the logic is not right.