You are correct on both points, generally you earn 2 rail points for each dollar spent, with the two exceptions that

a) you get a minimum of 100 rail points for each ticket (limit for legs per day), and

b) you get 500 or 750 rail points for travel between certain city pairs, a provisio that doesn't include Baltimore and Wilmington.

Note that Amtrak often has promotions, as well. Right now you can get double bonus points (triple later in the month) on each trip. Bonus points don't count towards status, but do count towards award travel.