You have the basic concepts down, like moving in upper inner link positions down raises the roll center and vice versa. You'd be surprised how many people inverse those. But your above statement isn't really correct. Many people inadvertently confuse the CG with the RC, but it is their relationship to one another's position that actually affects the way the car handles.

In your example, we really wouldn't know anything about the position of the bus's RC unless we knew some details about the geometry of the suspension. But we can assume it's somewhere and for the purpose of this explanation, assume it's located at ground level. Now, the reason the double decker bus tips or rolls in turns is because it has a high center of gravity, and the distance between the CG and the RC is large. If I was to adjust the bus's suspension and raise the RC closer to the CG, the same bus would actually roll less in the turns.

The CG always acts about the RC, so the closer the two are together, the less the CG will seem to act. Think of it like a torque wrench-if the handle is long and you exert a 10lb force, the bolt moves easily. But if you shorten the handle and apply the same 10lb force, it's much more difficult to move the bolt. The moment arm (distance btwn the CG and the RC) is what you're actually changing when you move your RC. As you get further away from the CG (lower RC) the car rolls more. The closer you get (high CG), the less the car rolls.

There are a whole host of other things to consider also, like the relationship between your front and rear roll centers (roll axis), roll stiffness, dynamic roll center, etc. but that's a topic for another day.