Hi @famador, answering your second question first: A "haversine distance formula" is the de-facto one used to calculate distances. There's quite some theory about it given on this page: https://www.movable-type.co.uk/scripts/latlong.html
Searching the net for "lat long distance calculator" throws up many results - online tools where you can paste in your values and find the distance.
Coming back to the first query : I was able to properly make a KML of the sample data you provide, using the same script. (it's just two locations so just makes a line) Their location is somewhere in the middle of the ocean.