Are there any places within Jotunheimen National Park where I can buy food, shower, recharge electrical appliances etc.? Looking for things like cabins, hostels, RV-places, whatever. Much appreciated!
Yes, you have lots of places. First of all you can check out this site: http://www.visitjotunheimen.com/en/
Inside the Nationalpark you can hike between the cabins of the norwegian hiking organization. Read more here: http://ut.no/turomrade/jotunheimen and here: http://www.turistforeningen.no/english/location.php?lo_id=NO_jotun&fo_id=3980
In Lom you have to visit this gem, http://bakerietilom.no, it's the greatest bakery ever about 6 years ago