Very good. I am glad you found a data set using decimal geocoordinates.You also could have written a small Procedure to convert the dd,mm,ss to decimal ...
Yes it is possible to add an infobox from the geojson information. The CreateMarkers only creates a Marker at the location. The National Parks tutorial demonstrates how to plot multiple run time markers using a csv file to an OpenStreetMap and how to create and populate the info box. Use the ideas there by selecting the items from the geojson data stream (similar to how you isolated the latitude and longitude) to provide what you want (perhaps location and UIV number) in the infobox. Instead of the csv, use the topics parsed from the geojson.
Yes, you will be able to click the marker to get the popup. Try the tutorial and see how it works. It is probably what you want to do.