The transportation isn't that bad. My flight tonight is from Philly to Detroit through , then from Detroit to Tokyo (Narita International) via Northwest Airlines. From Tokyo you can easily take domestic flights (ANA, JAL) to Sapporo. Or if you want, take Shinkansen to Sapporo so you get to see the entire nation.
Don't worry about the snowboards, they have plenty to rent there. And for motels , you can rent some in Sapporo , or in the surrounding towns around the parks. There's plenty of english-friendly hotels/ motels/ cabins there.
Sapporo is pretty international city tho its small. Lots of European tourists there any given time, so im sure you'll find some German groups there. But if you're there, i'd recommend you to mingle with the local people buddy. Japanese people are very friendly and if you tell them you're from Germany, they'll be asking you so many questions LOL.