First I see you are using PLA animation. The issue with PLA is that you can’t do any kind of easing which looks very robotic. Instead of animating the points directly, link each point to be animated to a null through expresso, then animate the nulls – you can do any easing you want on the null animations AND every animated point can have keyframes now where ever on the timeline. They don’t have to be all keyframed on the same frame anymore. The points of the spline will follow the nulls you have linked to them. If you are using R19 you can ease PLA now.
For points or objects sticking to the plane of the cover, you can link their positions (in expresso) to either the spline that makes the cover deform or to the polygon that makes up the cover itself.
For the spline, you can use a spline node and choose how far along the spline that point sits, then you can offset that point’s x, y or z to get it higher or lower on the cover. When the cover moves the point will always move with it, just offset by the amount you choose.
For the cover polygon, you can get the position of that polygon in expresso (in world space) and pass it with an offset to your point,.
Or, maybe more simply, use that polygon as an emitter object for a mograph cloner; choose object and let it make one clone in the center. Even if the cloned object is not the one you want, you can then get the position of that clone and pass that to your point.
Because you are using an IK chain you can also child the object you want on the cover to one of the bones and that will position it where ever you set it to be and that object will follow along with the book deformation without actually being deformed itself. (we do eyeballs in heads like this, they are part of the iK chain and not part of the mesh or skin heirarchy)