A: My apologies. There was a bullet point that indicated that it was sold separately and it must have been removed. Thank you for bringing it to my attention as I will put it back. The hold down bracket is Thetford part 92415. It is indicated in the PDF of the instructions that can be found under the header "Info and Guides" on the Home Depot listing page, it is sold separately. The Home Depot offers it as there SKU 306520878
A: That is a great question. I appreciate you bringing this to my attention. The honest answer is I do not know but will get this resolved. These questions are routed to the supplier not to Home Depot. So I can confirm that the manufacturer does provide a one year warranty. This is confirmed by the PDF of the warranty that can be found on the product listing page. Why Home Depot indicates a three year warranty, I can not explain. I assume it is a data entry mistake. I will get that resolved. If it is not and there is something I am unaware of I will instead instruct them to modify the listing to explain the longer warranty in detail.
A: I think you are seeing the optional floor plate. This is a plate you mount to the floor and the toilet quickly attaches to and can be released from. It is Thetford part number 92415 and is offered on Home Depots web site. If you put that number in the search block it will come up.
A: The clean water tank holds four gallon. To flush you push the flush button and water will flow into the bowl for as long as you press the button. So it depends on how much water you use on each flush. An average flush for my use probably uses about 4 oz of water.