Yes, there's a lot of different wifi adapters for laptops. Most of them are just plugged into a USB port and are relatively inexpensive depending on brand.
If you've been in an airport, coffee shop, library or hotel recently, chances are you've been right in the middle of a wireless network. Many people also use wireless networking, also called WiFi or...
It depends on what kind of adapter you are speaking of. Netbooks are just smaller laptops and have many of the same ports and connections that a regular laptop would have. Chances are that it should...
Basically yes, any laptop with wifi capability and within wifi network will work. Other factors might contribute, is the wifi has public access, can you connect your laptop to the wifi network...
a laptop is designed to be easy to transport and has its own power source. Usually the entire PC + display make up one unit (although there are desktops that are also in one piece)