Order Quantity and Order Status

Hello,

I would like to add a 'Backorder' order status to the current ones available 'Received, Paid, Shipped and Closed'. I may also want a 'Partial Shipment' status as well. Can this be done? If not, how do you track orders that are partially shipped?

Once shipped, I would like to add a tracking number in a field somewhere. Is this possible as well? How does everyone track shipping on their orders?

I would also like to be able to restrict the quantity order for some products. For example, a user can only order or put into the cart one of 'Product A'. They should not be able to edit it during checkout and multiple 'Add to Cart' clicks should also not add to the quantity.

Any help would be appreciated!

Thanks!