For the dumpster, an archiving process will not make the dumpster grow unless you say delete original and dont create shortcut, as the archiving process is just an edit of the existing item.
With Virtual Vault if you drag a load of items from one place to the other, it will cause the dumpster to grow as when you move an item from inbox to virtual vault, its actually a copy and a delete.
With Legal Holds and Versioning in Exchange 2010 you would see the exchange database explode, for the fact that you have the original item, you then might reply to it, so you have two copies of that email, you then archive it and it first goes to pending, so you have a third copy and then it becomes shortcutted, you then have a fourth copy
There is some back and forth regarding White space reclaimation with Exchange 2010 and i believe something may be coming out fairly soon from microsoft to deal with the issue, as some customers are seeing a lot of used space in their Exchange Database where as the mailbox sizes remain fairly small.