Yes - they are saying that the fluid pressure inside the tubing will constant at 0.05 atm because you're basically just adding more fluid without changing the potential energy of the mass of fluid because you still have the same column of fluid above the tubing. This is akin to measuring the pressure at the bottom of your pool, then expanding the pool so that instead of having a small pond, you now have an Olympic sized pool. You can go and measure the pressure at that same point on the bottom again and you'll find the same pressure. You've added more fluid, but you haven't changed the height of the column of fluid above the point of measurement.
I'm not sure about the tanks at different heights - that's an interesting scenario. Intuitively, I would guess that you're right and you could just average the two. The reason I think that is because if you had two identical tanks filled to the same height with one more elevated than the other, the higher tank would exert a greater pressure on the tubing than the lower tank, which would cause the water to rise in the lower tank until the water levels in the two tanks were equal. Since these tanks are identical, the linear flow rate out of tank 2 would have to equal the linear flow rate into tank 1. In other words, tank 2 would fall the same height that tank 1 would rise. That's just another way of saying that the added height you had before is now distributed equally over the two tanks (assuming that the tanks are tall enough so that the fluid doesn't just come flowing out the top). Which would mean that the new height is just an average of the two old ones.
It's easier to imagine an example, so say initially you had a 10 m of water in each tank. Tank 2 is 5 m above tank 1. So in effect, your "h" for tank 2 is 15 m and your "h" for tank 1 is 10 m. Now, the water levels will equilibrate as outlined above until the heights are the same. Again, since the tanks are identical, the loss of height of one is the gain of height of the other. This means that you will lose 2.5 m from tank 2 and gain 2.5 m in tank 1, making the h the same in both cases, now 12.5 m. Now it becomes the same problem as the one you're asking about.
That's my take on it - I'm not a good physicist so there's a good chance it could be wrong.
