Hi Tomaso,
We have biked all of your route except the piece from Toulouse to Orolon. You'll find a bit on some of the routes here:
http://www.caminodesantiago.me/community/threads/cycling-various-caminos-good-better-and-best.16273/
I noticed I still have not added the route from Menton to Arles, the voie Aurellian. or the Arles route, so it isn't that useful.
The via Della costa is described in the link. It has some really steep climbing, as in the hardest climbs between Genoa and Santiago. 50 km a day can be a lot. At least you know how best to get out of Genoa!
The route from Menton to Arles the voie Aurellian (GR653A) is really pretty tough until Frejus. We rode many nearby detours until there, then stayed pretty much on the trail. If you want to follow the marked trails from Genoa to Arles you will need far more than a week.
The Arles route is quite reasonable in comparison. A bike will need to detour some near St Guilhem le Desert, and from there to Castres I describe the Haute Languedoc as "the Appalachians on Steroids". After Castres it is much easier, though it runs around a fair bit near Toulouse and the canal road is a nice alternative.
From Toulouse you can ride north 60 km and join the route from LePuy, or continues to Orolon, and jump up to the Lepuy route and SJPP on the Piedmont route.
If you pack lightly, 50-60 km a day will be no problem from SJPP to Santiago. It will be a fairly hard day in some of the mountains you'll cross.
We will be in Cotignac, just off the Voie Aurellian from May 3-23, if you want to stop by for a bike tune up and dinner.