Need train tickets to above. en-voyages.sncf website does not allow e-ticket and does not mail to the US(?). Picking up tickets there (prepaid) makes me a little nervous - should I be? How best to secure this trip?
No need to be nervous. First, buy only one ticket at a time; in other words, check out with only one ticket in your shopping cart, and repeat the shopping process if you need more than one ticket. If you cannot print the ticket at home, select "pick up at a French station." Then, print out the page with the confirmation number. Bring the print out and the credit card you used to book the ticket to any French station, or to any SNCF Boutique (free-standing ticket offices in cities). They will issue the tickets quickly, and you're set. It's no different than booking a theater performance and getting your tickets at the "will call" window. Before the advent of print-at-home theater tickets, this was how LOTS of people got their tickets, and it worked (and still works) fine. You do need the credit card to pick up the ticket, but as long as you have this, no problems.