The bird should provide the temperature or heat to the egg. As long as the egg does not increase the temperature the birds should treat it as if where one of their own. No the noise thing is a sensible question. The answer is I'm not sure, if the noise is from or in the enviroment I would sugeest that they would, if it was a new noise start to ignore it quite quickly. If the noise wa to comes from the egg there might be a risk of rejection with by the bird removing the egg from the nest or the birds leaving the nest.
When we added cameras to the nest site it took a week or so for the birds to stop staring at the camera. Vultures don't like change... 
Making sure that there is no risk to the vultures is critical. We have not had a problem with any of the birds damaging the dummy eggs but they do damage the real eggs by accident normally by standing in them. There are also birds that will destroy their own eggs. Fire, poisoning, death are all things that I would like to avoid.
Many be rather than potting the device, because of the depth of the DS18b20s the case will be thick enough to protect the contents.