David's is a company name and they have many agents. They are a broker, so yes, they facilitate reaching out to the pool of owners they have in their database that are willing to rent the points. They liaise between you and the owner to complete the booking, so you never communicate with the owner directly. You pay more per point for their service versus working with an owner directly, but its recommended to use a broker for your first time or two until you understand the risks and implications.
Yes. They will provide you with the confirmation number. I'm not sure what format David's sends it in (I've not used them before), but the owners I have worked with have sent me a screenshot of the confirmed booking with the confirmation number.
A DVC owner is booking your reservation with their personal points that they own and pay for. They have deadlines by which they have to bank their points by if they are not going to use them, and if not done by that deadline, they lose those points for the year. If you were allowed to cancel your reservation, the owner would likely be out their points or have difficulty re-renting them by their banking deadline. And because the owner is laying out their points for you at time of booking, that is why full payment at time of booking is required.
DVC is a timeshare. The villa units are akin to condos, and Disney refers to DVC as your "home away from home". This is why the villas have kitchens, laundry, etc. Because of this, daily housekeeping is not provided. I believe they do collect trash daily, and they will do a full cleaning on day 8. I think they also replace towels around day 4. But otherwise, you're expected to treat it as if you were "home", so to speak. If you book a villa directly through Disney (not renting points), you would receive housekeeping daily and you can also pay extra to receive housekeeping, but I'm not sure of the cost off hand.
June of 2020? or 2021? You mention putting in your request 11 months out, so I am assuming you mean June of next year. June is a popular time but if you can be flexible on dates, room type and view, your chances are good. Only Aulani owners will have their points available for rent at 7-11 months out. Whether you can secure a reservation solely depends on how many Aulani owners are renting their points through David's (or whatever broker) at the time you are inquiring. If they have none available, they will add you to the wait list. At the 7 month mark, any DVC owner can rent their points for a stay at Aulani (or any DVC resort), so point availability will greatly increase at that time. Also, its worth noting that if David's can secure a booking for you between the 7-11 months out, you do pay more per point for that. Some are willing to do that to ensure they get what they want. But otherwise, if you wait until 7 months or less, you pay less per point. Not sure I'd recommend that if trying to book for June though.