How can I print a number of copies of a document (Y) and add custom text at the bottom "Page X of Y" where X is the number of the copy printed 1, 2,...7.. etc.?

You would need to print the file using a loop. Let's say you have a field called "Counter" where you want to place this text. The basic code to do it would be:

var y = 5;
for (var x=1; x<=y; x++) {
    this.getField("Counter").value = "Page " + x + " of " + y;
    this.print();
}
this.getField("Counter").value = "";