Javascript query of JSON data file

Actually my original question was answered by Alexcode in a post named "XML query in Javascript"  I have a follow up question and didn't know if it could be viewed in the original post since it's closed.   As such the javascript that Alex presented is noted there.. Works wonderfully.   Please read it for the context of my follow up question..

I want to return multiple values of the query result.  If I query by "i" which is airport id I also want to return the "n" airport name and "t" and "g" the lat/long values.   I'm not sure how to do this.

Additionally, I want to move the JSON file to be external to the script.  How does this get named and also how do I reference the external JSON file from within the actual script doing the lookup

Thank you in advance for your input...