In June I have a roundtrip booked in C to ZRH, and I'm considering taking the train over to Vienna to visit a friend for a couple of days in the middle of the trip. The thought for the return is to book a one-way award ticket (probably on Swiss or LH) for VIE-ZRH on the morning of my return to the US. A couple questions:

Is two hours a reasonable connection time in ZRH? I don't remember the airport being all that big, but it was a while ago. Arrival would be Swiss or LH, departure on UA.

As a UA 1k, do I need to worry about baggage limitations on the one-way section? Both the swiss and LH websites mention zero baggage allowance on "economy light" fares, I'd like to confirm that my award ticket will book into something that allows two <=23kg bags (one plus another for being Star Gold).

Any reason to think they won't check my bags all the way through at VIE?

Anything else I need to worry about?