I'm going to be landing in Marseilles and going to Juan les Pins, then to Cannes. I've given up returning to St Tropez on this trip. From Cannes, I need to go to Apt - or as close as I can get with public transport - which I believe is Aix. I don't anticipate visiting Nice; I've been there many times while working in Europe.
The strike is the most worrying thing at the moment. Posters have given me the links for transport so I have a plan for how to get between these cities - but if the strike occurs on Oct 18, or if it is a multi day strike or spreads to multiple forms of transport, then I have a considerable problem.