This morning I got an e-mail from a long-time reader (her term) who is French but has lived in Australia (Queensland) for a long time. She sent me a link to a web page entitled Successions in France. It's pretty interesting, and probably explains things better than I have done.
Here are some quotes from the information on the Successions in France page. The underlining for emphasis is mine:
The law applicable to personal property in the succession is the law of the country where the deceased had, at the time of his/her death, his/her habitual residence.
On the other hand, for real estate, the applicable law is that of the country where said property is located. French law does not authorise any derogations from this rule, so that it is not possible to choose the law applying to a succession.
For personal property, even property located abroad, the French authorities are competent if the deceased, irrespective of his/her nationality, had his/her last domicile in France.
However, the French authorities consider that, in principle, they do not have competence for real estate located abroad.
French law does not provide for a choice as regards the law applicable to successions.
I do know that inheritance laws and estate tax rules are evolving in Europe and therefore in France. I hope the information above is up to date. The only way to know is to consult with a notaire.
As to the need to have a last will and testament (un testament) in France, I think this is the most relevant consideration:
If the deceased leaves a spouse: The surviving spouse receives all the estate where the deceased has collateral relatives. Where there are parents, half of the estate devolves to the spouse and the other half to the parents.
Under French law, only the deceased’s descendants (children, grandchildren, etc. provided that they qualify by their rank) and spouse are entitled to a reserved portion. Ascendants and collateral relatives do not have rights to reserved portions.
If you are an expat living in France, have a spouse or a PACS partner, and also have parents who are still living, the will and donation, including the donation au dernier vivant, provide a way for you and your heirs to plan for the day when you die. If your parents are elderly and live in another country, outside France, they might not want to inherit property in France, under any circumstances. It could really complicate their existence — not to mention your spouse's or partner's.
If you have children, whether from your current marriage or an earlier relationship, there's not much you can do about that in France. Your children are entitled to a set portion of your estate by law. In this case, without a will or donation, if:
The deceased leaves a spouse and children: Where there are children of the same parents, the surviving spouse receives, at his/her choice, either the usufruct of the deceased’s assets or the ownership of a quarter of the assets. Where there are children but not of the same parents, the spouse receives the ownership of a quarter of the assets.