As etna noted, meals have always been community seating due to the limited space in the dining car. That's a tradition that pre-dates Amtrak. And as noted bedrooms don't get shared, unless you are the one inviting a friend along.

Turning to the points question, it's a bit complicated. Both of you will get 2 points for each dollar spent on the railfare. You can find that amount on your ticket stub about 3/4's of the way down on the left side. Then whoever booked the actual reservation, will receive 2 points for every dollar spent on the accommodation charge, found on the right side of the stub.