How do I get a dropdown list to provide more information once the choice is selected from the list?

As 'Validation' script of Dropdown field use something like this:

var f1 = this.getField("Location Name");
var f2 = this.getField("Address");
var f3 = this.getField("Telephone");
var f4 = this.getField("Fax");
switch(event.value){
case "Location1":
f1.value = "Location1 Name goes here";
f2.value = "Location1 address goes here";
f3.value = "Location1 telephone number goes here";
f4.value = "Location1 fax number goes here";
break;

case "Location2":
f1.value = "Location2 Name goes here";
f2.value = "Location2 address goes here";
f3.value = "Location2 telephone number goes here";
f4.value = "Location2 fax number goes here";
break;

default:
f1.value = "";
f2.value = "";
f3.value = "";
f4.value = "";}

Change field names to your actual field names and add more locations (before 'default' line) also  "Location1" and "Location2" are just examples, change those to your actual dropdown choices you have for locations.

In dropdown field properties, under options tab, check 'Commit selected value immediately'.