Happy Dog wrote
' it would be helpful to be able to verify at least some of the more verifiable things like -
Where could one find more info about the 15,000 people killed in France already'
That should be in the newspapers at the time. I was in central France for three weeks and the temperatures were in the 40's (degrees C ~ 100 F+). The holiday coaches (with old people) coming from Spain were reporting temperatures in the region of 120F.
The newspapers in England reported it and said the French Government were considering it a healthcare scandal as many of the deaths were old people.
You should be able to find it in UK newspaper archives around July/August 2003.