Hello Lucas
I walked from Lourdes through St JPDP last September. I am away from home at the moment and haven't got immediate access to information, but yes there are refugios along the way - not many but very nice and simple. I thought it was a wonderful and enjoyable 6 days to St Jean. VERY few walkers, just four or five of us who met up most evenings. Throughout the walking day never met anyone. Quite a shock to turn the corner for the final approach to St Jean and meet the crowds. Big crowds!! I used that website that was recommended:it has all you need, though I also had a French guidebook to the "Piedmot Route" which I abandoned in St Jean. I can probably find the details for you. The path is very well signposted but much more subtly than it is along the
Camino Frances in Spain so you need to keep your eyes open!!
Yes you can get a credencial in the main information centre just inside the St Joseph gate inside the "domain" at Lourdes. I didn't get one myself, but I know they had them for either one or two euros and they were very friendly!
I will contact you when I get my old information
Buen Camino
Tim Redmond (from Liverpool. Currently in Berkeley California)