To get out of Lorient the best spot may be at Lanester. Take a bus (line 31, 40, 24) from the city center to Parc des Expos about 3 km east. There's a big Shopping Center, exhibition grounds and McD's.
Just after the big roundabout, on the slip road towards Vannes/Nantes/Rennes, you will find a good location where cars can see you and pull over easily. It has always worked for me in less than 20 minutes.
It's a bit more complicated west towards Quimper.
There is another spot going all directions and always going throught the lanester roundabout (if you can't take the bus) it's the rond point de la base sous marine, behind the géant.
To get to lorient you have to take a detour from the main axis nantes-brest, so if the driver doesn't have time ask to be dropped off in lanester, from there you can either walk 2-3km and you'll be in lorient (follow the signs) or hitchhicke on the roundabout going towards Lorient, doesn't work very well but it eventually does
Check out bus company website: www.ctrl.fr
Places to Visit
There isn't much happening in lorient most of the time, but there is the sea close by (take the bus 30 to fort bloqué, it's quite nice) there is one big event during the year called le festival interceltique where the population becomes 10 times more important, it's one giant party, it happens beginning of august to the 15th
Places to Avoid
Accommodation and Sleep
Lorient itself is not very open to hosting strangers, there used to be a bunch of squats but over the last 20 years many have closed, perhaps there are a few left but as a local who'se been living there 10 years i have never heard of any. Otherwise during the festival you can plant your tent in town in relatively safe places like behind the halles de merville, or at the ter, otherwise there are some nice places in the countryside between lorient and ploemeur or lorient and pont scorff, where people can't see you or don't care
Other Useful Info
Best time to come is during the Festival Interceltique, beginning of August.