Prices can vary by sailing. You can look at the planner price via the web tool and sorta determine what the on board price is from that. You can get discounts on board sometimes.
You can do it all on one device, like a laptop. Pull up the SetSail pass w/ barcode in the planner, save the image of the barcode and upload that image to an online barcode decoder.
As with most of the bids, much of the info could be for marketing purposes (how much are people willing to bid or raise their bid), not for actually winning a bid.
The very few times this was reported, I seem to recall folks having to pay full price for all the drinks they did consume and was done earlier in the sailing.
Yea, but unlikely. You should find out your assignment (via the barcode trick) at 45 days out when you check in.
The available list you see is normal - the list is usually limited to two major categories above your existing cabin category.
The cruise contract you get at 30 days out has the same language as the T&C listed on the RCI web site:
United States CTC EN - Guest Terms and Conditions (royalcaribbean.com)
Those T&C are specific to the market in which you booked - the Aussie T&C is a bit different than the US one linked above.