score:5
If you've purchased it as part of a single itinerary, most likely the answer to your first question is yes. Generally, if the carriers are part of an alliance or have interline agreements, then your bag would be through-checked in to your final destination. You can confirm this at the ticketing counter.
Answer to your 2nd question is most likely a yes as-well. But, it could change and you might have to get the boarding passes separately once you land in your connecting airport.
Yes, since United it is all under a single itin and United is the one that ticket this for you, you'll be taken care, in case if you miss the flight cause of delays caused by flight operations.
Upvote:2
just to be more affirmative about your last question:
If my ORD->BOS flight is delayed so I miss the flight out of BOS, will United (or Lufthansa) be obligated to get me from BOS to TLV?
Absolutely yes! United is fully responsible for all your flights as you purchased it from them and they provided you the best way to get from point A to point B. Note that it's all on the same ticket number.