Travel in Seoul

[Simon59]

My first name is Simon and I'm French (24 years old). In three months I will travel to Seoul, that's my first trip in South Korea. I'm fascinated by Korea since I have started practising the roller slalom. In the beginning I watched a lot Korean videos of roller slalom, then I became interested in the Korean culture (films, drama/comedy series, music, etc).
I don't know where people practise the roller slalom in Seoul. A friend gave me only three locations:
- Olympic Park
- Yeouido Park
- cycle track along the river Han


Question no.1
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Where is this location? (see the video in below)
http://hepac.urinet21.com/KFSA/2005_07_16kfsa.wmv
Is it far away from Seoul? Is it the address for Angyang Slalom Contest?

Question no.2
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What is the name of this subway station? (see the video in below)
http://www.youtube.com/watch?v=Njg2GC3-0pM

Question no.3
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What are the other locations of the roller slalom in Seoul?
And what are the other well-known subway stations for the roller slalom?

Thanks in advance