I'm not sure what you're getting at with 1- I don't think any service ever can transfer files to a machine that isn't on. As soon as the co-worker shows up on Monday, the transfer will finish.

As far as 2 is concerned though, that is not the case. Don't forget, it's built on top of BT. As each piece of the file gets transferred to other clients by the original machine, the other clients will be able to send those pieces out too. In theory it will be faster than a transfer from a central server.