Thanks for all your input.

I will make up my mind if I go to the class at all or not. It sounds like it is very tight. If I attend this class, I will definitely take a taxi to either Kowloon or Tsing Yi and then the Airport Express. It doesn't sound too bad in terms of time but saves me from taking the taxi all the way to the airport.

A lady from HK told me yesterday, that HKIA regulation is that everybody HAS to be at the airport 2h before the flight but she admitted that she doesn't fly very much

I saw the Dragonair codeshares. Of course I could book these too but they are not part of the CA promotion fares, they don't earn me any miles on Lufthansa and also I want to get to Beijing as early as possible. So if I decide to not go to that class, I will even take a flight earlier in the morning to expand Beijing (first time for me) time.

Thank you so much for all your input, you guys helped me a lot!