They should check your bags through and 2 hours would be more than enough time assuming your inbound is on time. While I do know that a UA award will not book into a "light" fare class, I'm not going to wade into the checked bag quagmire . . . you will get multiple different opinions on what the entitlement is.

I do separate tix fairly frequently but a serious word of warning: If you are on an LX revenue ticket for the TATL they will have no sympathy whatsoever for you if you misconnect and will likely insist you pay a walk-up fare to get on the next flight. It is completely different from how UA handles that sort of thing. Note while LX and OS would be viable options VIE-ZRH, LH is not . . . makes no sense to connect via MUC or FRA.