What's the deal with "change of plane" flights, e.g., flight 605 IAD-SAN?

UAL.com tells me nothing about where this occurs nor how long the layover is (of course I can figure out that the flight goes through ORD by looking at today's status).

I assume that there are no extra miles involved and it counts as only 1 EQS? UAL.com says 1 BP only so what happens if the equipment changes?