Hi, oneday,
In the ten years that I've been walking Caminos, I've met many people over 70. One year, I was honored to participate in the birthday celebration of an 85 year old Italian man. We were in Castrojeriz, and he had been walking Caminos for many years. Another year I saw a man in his 80s who was jogging the Camino -- well, his jog wasn't much faster than many of the young guys' walk, but anyway, my point is that age isn't the only thing that matters. This year I met two 75-year old German men who walked/bussed/taxied and had a great time.
I think that whether you want to do the St. Jean to Roncesvalles stretch in one day depends on your stamina and hiking abilities. I'm not sure what the elevation gain is between St. Jean and the highest point, but it must be close to 2500 feet. I assume you have a pretty good idea of what your limits are in that regard. It is the only real killer ascent of the whole Camino, too bad it's on the first day, but I guess it's initiation by fire.
But in any event, even if you can do the trip in one day, you should consider the pleasure of spending an afternoon up in Orisson. I was there on a beautiful May day, we arrived before noon and had the whole afternoon to lounge around and enjoy. The views were stunning. Now, I had been walking from Moissac, so a rest day was probably more of a treat than it would be for you on Day 1, but in any event, it is really pretty up there.
I always bring a sleeping bag, even in summer, because honestly you will be sleeping in a lot of beds whose conditions probably don't meet your normal standards of hygiene. But you'll be fine. Asnd about the last question, as others have commented, bed bugs don't seem to be as much of a problem this year as they were last year. Who knows why. Enjoy!
