The S7 and CAT trains are in the exact same place, but all the signs 
just say CAT.  There are ticket machines down the ramp, if there is a 
line at the window.  The view from the train wasn't great, so the bus 
sounds like a reasonable choice (although Stefan says it's view won't be 
any better).
H&M sells T shirts for only 5 Euros if you lose your luggage :-).
Also, Stefan says that the 'bar' can possibly mean two places; there is 
a fairly small area downstairs, and apparently a larger area upstairs 
(which I have not seen)  So if you're looking for people, you might 
check both places.
Michael, I think it's just me and Aaryaman here so far, and I'm out with 
jet lag now :-(.  I gather that Alexandre comes in with jet lag of his 
own any minute now.
I think it is likely that an expedition will set out tomorrow between 
8:30 and 9:00 am to visit the Schönbrunn Palace.
Cheers,
Jeremy