Any ideas? Which train do we take from Amboise to Paris (St.Michel-Notre Dame)?
You can go to the sncf website at www.sncf.com to double check this info (when you get to the home page, there is a little british flag in the bottom left corner, click it for English).
It appears that you take the Corail Intercites train from Amboise to St Pierre des Corps and then transfer to a TGV train which takes you to Paris Montparnasse station (and then you'd have to take the metro or a bus to Notre Dame).
There did appear to be a direct train from Amboise to Paris Austerlitz, but you don't save any time because it is a slower train than the TGV.