Firstly, congratulations on your perfect written English, which makes me wonder whether perhaps you are not new to the US. As a fellow European, I can understand the difficulties with cultural issues concerning community and housing developments. The Roman town planning of “Il Centro” doesn’t exist here much, rather suburbia with emphasis on convenience pervades.
You have asked the right questions, and have come to the right place to ask them. As many have suggested, hold onto your Euros, and wait for house prices to come down. I am in the same situation. If the dollar starts to gain ground before house prices bottom out, I might be tempted to exchange at the best rate I can, and then sit on the dollars until I’m ready to buy.
I personally like Encinitas because it’s village-like, on the coast, with small restaurants and local wine. The areas just east of it towards Rancho Santa Fe (trop chere) is nice for a drive. You will be aware of the huge fires, and I believe there will an updated map of fire prone areas in 2008. This may be a consideration.
Although very expensive, La Jolla is nice, with swimmable beaches, restaurants perched on a cliff overlooking the sea, and a small community of shops. How much cheaper or what the areas next to it are like, I’m not certain, but having somewhere like La Jolla close by might make the transition smoother.
I have bumped into several French people living in San Diego, so perhaps there is an French association or club you could join, and ask your fellow countrymen’s advise.