Debbie,(posted 8500 days ago)What you need to do in the first instance, now that you have found this site, is read it thoroughly. At the very least you must read the Repossession section. The answers to some of your questions are already there.
I always thought that arrears could be paid off over the whole period of the mortgage (Norgan rules), but I think maybe this needs to be agreed in court? Obviously I don't know all the facts in your case and I'm only going on what I've read on this site anyway, so I hope someone else may have some opinions?
From what you say you need to be satisfied that the lender did in fact sell the property for the best value. If you any doubts, keep asking for proof and evidence, and avoid filling in an I&E form. That's my advice, for what it's worth.