1. Yes. Send the land registry document showing their ownership, and a letter from them expressly giving the applicant and sponsor permission to live there. You'll want the letter to state how many rooms (excluding kitchen and bathroom(s)) there are and who will be living in the house.
2. The savings account is the easiest route if you have it. You would just need to show six months of bank statements showing the applicant and/or the sponsor (but nobody else) has held the savings for a full six months. The amount needed is £62,500. At today's exchange rate, that is about $81,700 US. They will use the Oanda.com closing rate from the date you submit and pay for your application, so if it's close be sure to watch the exchange rate and don't apply on a date when the value drops below the amount you need.
3. Ask this when you get to the actual question on the application so you can tell us the exact wording. My instinct is to agree that for you the answer is 'yes', but without seeing the question, it's hard to know exactly what they're asking.