I haven't hiked it but being local to me I can tell you a few things.
It's more a countryside trip than anything else. You cross some mountains but it's all over good paths. Usually, you're on the plains, hiking from village to village so no wilderness at all.
Few people take camping/sleeping/cooking gear. Most stay at villages along the way. There's a dense network of hostels specific for this trail and a wealth of other accomodation options. Most people carry food just for the day. Your pack might be ridiculously light but you'll find that most people still carry kind of monster sized packs: many hikers on this trail are inexperienced and tend to carry lots of things. Also, people tend to tidy up more than in a backcountry trip so a lightweight, bare minimum approach to clothing that's fine in the backcountry may not be so much in order. People are in town several hours a day, every day.
There's certainly an end point but not one starting point. Most typical is Saint Jean de Pied de Port, on the Pyrenean foothills just north of the french border. If that's your starting point, you'll be throught the most scenic part of the trip on the first few days. After that, it's several hundred miles of plains and rolling hills and only close to the end you'll have to cross some mountain terrain. Remember this is an ancient pilgrim route, it wasn't meant for scenic value but for ease of going.
Summer is very warm and busy. The weather is quite similar to Southern California. I'd say the best time would be april to june or september to november but that's very subjective and depends a lot on what you're looking for. This trail is more a cultural experience than anything else, lots of people from many different countries so the busy times may be nice for the most social interaction… but many find them too busy.
You should be able to find lots of info on the net and given the number of english speaking hikers on this trail I'm sure there are lots of resources in english