Hi,
I can't offer advice on all that you are trying to do, but if you cloned the feature to avoid forking you should also have cloned the mojogmaputils3.js into a new file with a different name and then change your code to reference the new file and use a different key when registering the script. Otherwise if you modify the mojogmaputils3.js you are forking that file and possibly breaking the built in google map and if you upgrade the file will be replaced by the original, so a clone should not have any files in common with the original feature.
Maybe someone else here can offer more help with extending the map functionality, or there are probably lots of tutorials or example code to be found by googling.
Hope that helps,
Joe