My wife is booked on a UA award ticket IAD-FRA-LEJ in a few weeks. Checking the itinerary today, the FRA-LEJ segment was changed from a flight (LH156) to a train (LH3770) to Leipzig Hbf / XIT. I have a few questions:

• Would she likely get her boarding pass / train ticket for FRA-XIT when checking in at IAD, or would she have to get it somewhere at FRA?
• One of the previous posts mentioned that baggage for such an intermodal ticket would be delivered to a separate pick-up area near the AirRail check-in in the walkway/bridge between the airport and the long distance train station rather than the regular luggage carousel after immigration and before customs - is that still the case? If so, does the luggage need to be tagged IAD-FRA-XIT (rather than just IAD-FRA) even though my wife will be picking it up at FRA and carrying it on the train? I'm just wondering what to look out for during check-in and baggage tagging.
• If she misses the train to XIT indicated on her boarding pass / train ticket due to a delayed flight or long immigration lines (her connection time is about 1:40 hours), how does she get rebooked onto the next train? Would she have to interact with the AirRail staff in the walkway/bridge for rebooking, or could she just take the next train with her existing boarding pass? (obviously she could just purchase a regular train ticket for whatever train she ends up taking in that scenario, but it'd be nice not to have to do so)

Thank you very much in advance.