I can help with the first two parts...

To access and save variable data from another script, you should have that script attached to something in your scene. Just one copy of it.

Use this line:

var otherScriptObject : GameObject;

Drag that object into that variable in the inspector. You can also find it using GameObject.Find(), but this is the easiest way.

Then find that script from your first one with this line:

var otherScript = otherScriptObject.GetComponent("nameOfOtherScript");

Then you can refer to variables (and functions) in that script like this:

otherScript.someVariable = 3.14;
otherScript.someFunction();

If I understand part 3, you want to make a new script onto an game object? That's AddComponent()