Yeah, I've played, it's good fun
Well, since you're not originally from Sweden let me explain that Swedes kinda have rival history with every country around them, Finland, Denmark, Norway, you name it. They ruled the Fins for centuries I think, don't kill me if I'm wrong lol, they've fought wars with Denmark over some piece of land, and since Norway is perfectly seated beside Sweden, of course they automatically become both rivals and friends. They tell jokes on each other, I especially remember that Swedes make fun of how Norwegians talk. Ever heard Norwegian? Kinda sounds like Swedish if you're surprised when you're talking. Pretty funny I think.
You asked about the extra letters? Let me list them:
Á, á = "brother" of A, it's not a stress comma though as in Spanish, sounds like German "au"
Ð = "brother" of D, small cases it's "ð", many confuse this with a, but it's more like a D d . Sounds like "th" in English, "father"
É, é = similar to E, but it spoken like English "yeah" kinda funny
Í, í = sounds like the starting sound of E in the word English
Ó, ó = spoke like the word "owe"
Ú, ú = like oo in "fool"
Þ, þ = like "th" in "with"
Æ, æ = spoken like English "I" (as in "me")
Ö, ö = If you speak German or Swedish it's the same as the Ö there. In English, similar to the sound "U" in "under"
**** long and boring, but I hope that explains things