HP has a large commodity of parts for your notebook. It's actually quite unlikely that they don't have your battery in stock - the dv9k was in use by HP for a long time. I suggest you try a chat with them to find out where you can purchase one.
As for the 3GB RAM limit, it looks as though you have a 32-bit OS installed. Your computer cannot recognize greater than 4GB of RAM until you install 64-bit OS.