Most 6yos should be able to integrate within a year. I say most because my youngest was 6 when we arrived and she surprised us by becoming completely resistant to all things France/French. This meant she didn't want anything to do with learning the language. If you can, check with the schools and see what type of support the do (or don't) provide children that age who do not know French. The school my kids are at doesn't provide any for children who are 6 and in CP. Their rationale is that kids are just learning to read and write, they might as well be in the regular classroom. I think that was detrimental to my DD. No one at the school was actually helping her learn French - it was all on her to do it. (And us to hire a tutor)
As to whether to homeschool...the big advantage I see to that is that you are free from the restrictions of the school calendar. The negative is that it will be difficult for your 6yo to meet others. The number of families that homeschools is so small, that it is likely there won't be any others in your area. The laws are also such that if you are only here for a year, I think they'll look the other way if your child doesn't learn French and the French national curriculum. But if you stay for another year, there could be problems.
