For the first part, I’m 90% sure that’s already the case when possible, but the freight companies just make their trains too long for the sidings so Amtrak has to sidetrack instead of them.
For the second part, that is sometimes an option, but it isn’t cheap. I know there’s an Amtrak train that runs on the east coast that does that. It’s from DC to Orlando, FL. I don’t know if there are any other routes for this yet though.
Yeah that’s the only one, and I’m on the Left Coast. Looked into it when our kid was graduating in Minnesota and it was impossible. I wound up driving the whole way and back.
Yeah, sadly passenger rail connecting the two coasts is fairly poor. I’m sure a coast-to-coast passenger rail with car transportation could do really well. It has to be expensive, because a car is about the size of a cabin so you essentially need to pay for two cabin spaces plus anything else involved in it. Still, it beats that long drive by car and all the miles you’d put on your car. We really need to get rail moving to where it should have been decades ago.