Mark, you asked about the terrain and distances between accommodation.
I'm not sure if the guide for people with disabilites leads you away from the more remote pilgrim paths but here is a synopsis of the terrain from the website of the CSJ - with a few of my own observations thrown in. For accommodation, I downloaded the plan page from the godesalco.com website that has the distances between all the towns and villages and have it as a word doc - if you would like a copy please mail me and I will send it to you.
If you start from St Jean Pied-de-Port, the very first day involves a very steep climb climb of 1,200 metres, then a short, sharp descent to Roncesvalles which many find more strenuous than the ascent.
If you start from Roncesvalles, it's an undulating, mostly downhill, walk for 2 days to Pamplona. It can be lethal if muddy so watch for the weather forecast.
After Pamplona you climb to the Alto de Perdon, a little bugger of a hill with a steep, river-boulder strewn descent on the other side.
Thereafter it certainly isn't flat - I guess I'd call it undulating - till Belorado, after which you climb the Montes de Oca (an hour's climb, then a plateau) to San Juan de Ortega before dropping again to Burgos.
The meseta which follows is a pretty level plateau at about 800 metres, and takes about a week to cross - two weeks if you cover 10km per day. The mountains of León take you up to 1,400 metres over 2 - 4 days, then very steeply down to the Bierzo plain. The path down to el Acebo and Molinaseca is mostly shale and this, too can be strenuous walking.
2 days later you have the Cebreiro range, again reaching 1,400 metres, and climbed in one day - or two if you chose. But neither of these is as bad as the day from St Jean, because you start higher up. However, the path is mainly rocks which can be difficult if you are unsteady - especially on the downhills.
After Cebreiro it's generally downhill all the way to Santiago, but that doesn't mean that there are no more climbs ! Its pretty much a roller coaster of short sharp ups and steep downs all the way to Santiago.
Remember too that for many people going downhill is worse than climbing. The descents mentioned are steeper than the preceding climbs. Some guides are for walkers and cyclists eg: Practical Guide for Pilgrims - Millán Bravo Lozana - and if the paths are not recommended for cyclists, you'll know that they are rutted or rocky and in that case it would be better to follow the alternative, cyclist's route. (Which many pilgrims do - especially those pulling or pushing carts or those with injuries.)