I'll only try to answer your first question about trains out of
Zurich, but I'll be interested in the other answers that come up,
since I may be going to the Lake District next winter.
If you want to go as quickly as possible from Zurich Airport to
Lugano, on you can search "Zurich Airport"
to "Lugano." A pull-down menu comes up with many places in Lugano,
but you can just leave it at "Lugano" for the main station. Trains
leave from Zurich Airport, right below the terminals. For the times
I checked, you would always need to change at the main Zurich
station. Trains leave the airport at 43 past the hour, arrive at 53
past, then you can leave Zurich Hbf for Lugano at 9 past. The trains
from the airport to the city are more frequent than that, so if you
want to spend time in Zurich you can just take the first train, then
leave for Lugano on one of the hourly trains. Traditionally it
wasn't possible to reserve seats on trains within Switzerland; I
don't know if that's changed, but you should be fine going without a
reservation and just getting on a train when you're ready.