OK, it has been a while since I have been on a French train, and the SNCF site is sorely lacking in information on the subject, at least the English version. As there was a comment made on another thread (that I didn't want to hijack) that French trains are becoming harder to use with bikes, I am looking for some information on three different legs:

1) CDG to/from Paris. On arrival is it better to build bikes in the airport or transport boxed? Are bikes allowed on this train, I vaguely remember it being more commuter-style last time I was there a decade ago.

2) Paris to Nevers, or thereabouts, to start the Loire Valley cycle route. Any specific services to avoid/select? Or, is there a better option on arrival to get from CDG right to this point bypassing Paris?

3) Somewhere along the Atlantic coast between Nantes and Brest back to Paris, depending on how far we end up making it in the allotted time. Same as #2.

Can anyone shed some light on this?