Quite the same happened to me, but I was travelling with my wife (who does not share my family name but kept her maiden name). Her ticket however had my name printed. In summary: it worked out. But it was a little difficult. ;-)
Regarding your questions:
- Not that I know of. He checks the tickets as such.
- Yes, afaik they have exactly the same content as the ones that were available online.
- Yes. However, if you cannot somehow explain why your name is on your co-travellers ticket, you might have a problem (i.e. using the train without a valid ticket).
I would however suggest to contact them directly and explain the situation and get their opinion on the case.
https://www.tgv-lyria.com/en/contact-us https://help.en.voyages-sncf.com/en/contact