PORTBAR FOR ASUS NOTEBOOK

Hello!
My name is Andrea and I own a Asus L3800C notebook.
I'm thinking about buying a Portbar for my laptop.
My laptop has 2 USB ports and the portbar II from Asus, adquate for
L3C has also 2 USB ports.
I'm wondering if, when I have my portbar connected to the notebook,
using the USB ports, I can also use the 2 USB ports from the laptop
itself. What I mean is that if the Portbar adds two more USB ports to
the laptop or if just keeps the USB devices connected.
Another question is if the Portbar charges the laptop batery or if it
only keeps it on using the power suply, I mean?
Thanks a lot.
Andrea Oliveira