You must confirm shipment of the order with Amazon within 30 days of the order date. Otherwise, Amazon will automatically cancel the order and you will not be paid even if you shipped the order. One week before the 30 day cutoff, you will see a warning in Manage Orders (“Confirm as shipped by [date] to avoid cancellation”), and you will receive a notification by email.

depends on the warehouse, but could be anywhere between 0-3 days from my experience

It can take up to 5 days to process your product depending on the warehouse.

The quantity available for the listing is subtracted from the quantity in Manage Inventory. If there was a quantity of one at the time the order was placed, the listing will be removed from the Amazon.com offer page and appear in Manage Inventory with a quantity of zero while the order is being processed.