In auctions where the seller arranges shipping, a shipping estimate will appear on the auction underneath the bidding field.
If you click the blue circle with the white "i" in it, this will summarize the weight and dimensions of the product, the carrier the seller will be using, the service type, and the number of pieces comprising the shipment.
Reading the "Shipping" tab of the auction will give you additional details, such as information about additional fees for a liftgate, residential delivery, etc.
Auctions where the seller arranges shipping will always include the shipping cost in the order total.
If you win multiple auctions from the same seller, and wish to combine the shipping, you will need to first pay for each order in its entirety. Once you have paid, you will be given contact information to coordinate the shipping of your order. At this time, you can ask that your shipments be combined. If the seller agrees and provides a new shipping price, you can have the difference refunded in the form of a B-Stock credit that will be applied to your account.
For best practices in receiving your shipment, please review the attached file.
This blog post goes into more detail.