My general understanding is that when you have used the emergency provisions that BA offer, there is at some point a need to complete the journey as booked, other than on a different date. UuA is reversible anyway, so that makes sense. So to answer the question with the lmited information provided it's
1) No
2) The original fare conditions apply (with the UuA reversible) but if you want a refund instead then the original conditions / cancellation fee etc would apply.