Question about Sennheiser Pxc 550

The headphones can now be tried out in Zurich and other showrooms.

I have a few questions:
1. can I connect it to my PC via Bluetooth and use it for skype?
2. if yes: if the battery is empty and you charge it via USB, does the Bluetooth connection remain?
3. can I use it to control several sources at the same time?
4. can noise guard be switched off manually?

Many thanks for your answers :)

Unfortunately, the requested headphones cannot be viewed/tested in any of our shops. Only items labelled "Showroom" can be viewed in our shops. The corresponding shops are then listed under "Showroom" for the respective products.

Do you have any advice for me?