Our car attendant announced at each stop if we could get off to stretch our legs and how long we would be stopped for. I would not wander far from the car though. A few times the break was shorter than expected to make up time.
Roomettes have shared showers with the other roomettes. They look roomier than the shower in the bedroom compartment. Towels are provided but we brought our own travel size shampoo and shower gel.
Breakfast and lunch are first come, first serve. We went early before a line built up (and they may run out of favorite items).
Dinner is by reservation, the car attendant will come to you during the afternoon at your roommette to ask what time you prefer to dine. They will announce when to report for your time over the loud speaker in the car "Those with reservations for 5pm seating may now come to the dining room!"
If your party is less than 4 people, they usually fill in the seats. So you, your mom and sister would likely be sitting with a single traveler in the dining room at all meals. It's a fun way to meet new people. Our car attendant would call out, "If you are a party of less than 4, you WILL be dining with your future friends!"
All meals will be included in your roommette price. We did leave a tip in the dining room ($5 per 2 adults for brk and lunch, $10/2 adults dinner).
We also tipped $20 to the car attendant per night.
Not sure about the Southwest Chief, but the Zephyr had an observation car and lounge where you can visit and get out of the roommette for a bit.
As another poster mentioned,
youtube has lots of videos to help you get the lay of the land.
Happy Travels!