Apologies if this is already answered, but my flight this morning from EWR-IAD just got cancelled. Itinerary continues on to JNB and CPT later this afternoon.

There don't look to be any flights from the NY-area that will get us down to IAD in time, so I have 2 questions:
1) Will the itinerary get cancelled if we "miss" the first flight, or if we can make it down to IAD in time (fight to JNB isn't until 5:40 this afternoon), will we be ok?
2) Will United reimburse for any other modes of transportation (e.g. Amtrak, or even gas if we have to drive it ourselves?)

I'm a 1K, flying with my wife on 2 award tickets in business class the whole way.