Need Help finding present day relatives in Norway

Bernt Martin Pederson m. Gesine Gabrielsdtr Brekne -These were my great grandparents from the Lista, Vest-Agder area of Norway. They both died in Minnesota, USA. How do we go about finding if there are relations still living in Norway? We don't have any names of siblings, etc. beyond the 1900 census. Also we are interested in finding gravesites - if we know when a person died and where, would they normally be buried at a local church cemetery or were private gravesites on the farm common? What kind of information would we need in order to come up with answers to these questions? [?]