Recently purchased Sony Cybershot DSCW180. Took 3

Yes, you need to have memory stick because camera has limited internal memory that can store few pictures only.
Put new memory card, format it through camera Menu and copy internal memory pictures to memory stick, take our memory card from camera and delete internal memory pictures either one by one or format internal memory through camera Menu.
Thanks.

Yes. Apparently the internal memory is pretty small and the high resolution images can eat up the space very quickly. Read the specifications and check for the maximum size of the memory card your camera can support. Atleast 256-512MB is recommended(My 12 mega pixel cam eats up close to 1MB per image).

Regards,
Sai.