I would contact Deepak at Premiumplus-sports.com for travel arrangements. The swim is beautiful, in a warm, greenish, alpine lake that is 10-miles long (the lake is 10-miles long, the swim is only 2.4). The end of the swim is in a canal lined with spectators, which is cool. The bike is by far the prettiest place I have ever ridden a bike. At one point, you come down a hill with a crystal clear view of the Alps in front of you. You climb a steep hill lined with thousands of intoxicated specators blowing horns and yelling, "hup, hup, bravo" or "hup, hup, supa" There's chalk in the road - you have to get out of the saddle to make it up the hill. It's steep, but there is no way to get the smile off your face. You bike along the lake. 15th century church steeples rise out of the mountains. It's awesome. (The biking is actually so beautiful, that I accidently did a 30-mile ride the Thursday before the race - I knew this was too much, but it was so nice that I could not make myself stop.) The run is 5k along the lake on a bike path, then 5K back to transition, then 5k the other direction along the canal on a path into town, around the Lindwurm (dragon) in the town square and back - you do it twice. Awesome race. It's so beautiful, that it makes Ironman Lake Placid seem like biking through Newark.
I would buy some German language tapes, because not everyone speaks English, and at least trying to speak some German helps. I regret that I did not do enough sightseeing. My wife and I took the train to Salzburg. The train ride was 3 1/2 to 4 hours each way - it was pretty, but too long to be on the train, and Salzburg was really a giant tourist trap. We also saw the castle that snow white's castle was modeled after, which was a 10-minute taxi ride from Klagenfurt. That was pretty neat. If we had it to do over again, I think we would have rented a car, because it was hard to figure out mass transit, the Alps makes getting around the country difficult, and we did not see enough. Hanging out by the Lake is fun, renting mountain bikes and cruising around the lake is fun, and just relaxing in the town square is nice, but we did not really see enough of the country.
The food in Klagenfurt is fantastic. You really can't go wrong with the restaurants in town. The town feels very Italian, and it was actually built by Italian architects. The only bad thing is that there are lots of drunk people running around late at night, the hotels are not airconditioned, and the heat and street noise make sleeping very difficult. I had several nights were I got 2-4 hours sleep, and I did not feel quite right on race day. You might want to buy a fan when you get to town to drown out the street noise. I recomend booking your trip through Deepak, as he will make everything much easier.