Actually, all the roomettes come with seats - they're what folds out into the bottom bed at night (your cabin steward will do that; remember extra money for the tip).
It's been several years since I've taken the train anywhere. I only went from Boston to Washington overnight, and just got business-class seating. I had both seats to myself - most passengers opt for general coach, although it'd probably be different on a longer trip
A couple of people have mentioned the train running (hours) late. Amtrak doesn't own the tracks, the/a freight train company or similar does. Freight trains therefore get the right of way; the train's timing can also be affected by weather.
Yes, taxi (or town car) is the only option. Your friend will want to use the Kissimmee station, not the Orlando one. It's a little closer to WDW, but this is especially important on the return trip and moreso if they're not going for the roomette - since this station is smaller and not nearly as busy.
Totally apart from this, though - we have a family friend who, about twelve years ago, had a panic attack while boardng a plane home from Orlando and
refused to fly after that. He was using Amtrak to travel across the country - yes, all the way across - for a number of years.
He went to a hypnotist in Boston known as The Mad Russian - and it worked! He flew out west, just last year! Saved himself three and half/four days' travel! Why am I telling you this? Well, I'm guessing Long Island/the NYC area has equally well-known and effective behavior modification specialists. Your friend might want to ask around
