Where are you coming from, where are you flying to?

Passport control? Very likely

Walk is doable, don't worry. You can ask for wheelchair if necessary.

If on same ticket, your "competent" UAL check in agent should be able to get you a LH BP for the next flight. If not, make sure, at least your bags are checked through. For the BP, see the LH transfer desk, they will issue new boarding pass. Let them know if you have checked bags and if you have, have the baggage stub handy that you received at check in.