You might as well get one if you want to have the most current technology. That being said, you only need one if you actually need to connect to a 802.11n network.
what is a wireless g card with bluetooth?
wireless n is a type of wireless internet ("wi-fi)
what is a wireless card
Yes.
The same as with wireless G card and G router.
What is the Intel WiFi Link 5100 802.11 Wireless-N Card ?
Yes.
No. Wireless modems and routers have increased in the range that they can be picked up from. An N-modem and/or router as well as a compatible N wifi card should be sufficient.
You need to change the network card in your computer with a wireless one, and buy a wireless router. Need 2 items: wireless router wireless network card
Many people never use modem. If you are not using it either, you do not need. And of course you do not need a modem to connect to wireless networks.
If your modem has wireless interface, yes you can.
802.11 n