Hello! I have a problem for you guys
*Sorry for my English I'm French

I would like to build a stage composed with three superimposed plans.
The background is a set which can contain arbitrary graphic elements, by an image or a series of images.
The median plan is a time line on which are aligned objects (symbolized by icons)
The foreground allows the display in close-up of an object, accompanied with a note.
The navigation in the page is made with the scroll (horizontally or vertically).
Both plans of the background move by respecting an effect of parallax, the closest plan moving faster than the plan in the back which give a deep impression..
When a icon situated on the time line passes in the center of the window, it is " intercepted " and placed from the point of view of focus.
When an object is on this plan, it is associated with a note wich give its definition.

The problem has 4 parts:
1) Find a method to make a scroling of the graphic elements (Parallax?)
2) Determine if an icon of the line of time line is in the middle of the window
3) Resize the icon and show the associated text.
4) Move the HTML element associated with the icon of the branch
DOM " Time line " towards the branch "Focus ".