Some of the pictures are self explanatory. Beside rain, you will ride on agricutural areas. For instance sugar roots trucks in the north. ´Manure here and there etc.
I did some wild camping in the Netherland, it's really hard to find remote places, it's the same in most of Belgium. It's much easier in France and Spain. In France there's always drinkable water inside cemeteries. In Spain it's fountains at the centre of the villages.
Euro Velo are, from my point of view boring, I particularly hate the Via-Rhona which is straight and flat.
some french cities have relatively unsafe suburbs
(Valence, Nîmes, Beziers, Narbonne) : always keep an eye on your tandem.
The road from Argelès to Portbou is worth the trip !!
feel free to ask