Hi, Q1. For instance , Location A ( My Home ) and B ( My Cousin's House ). Ive install a wireless router in location A where the frequency can reach location B. Is there any other device that detect the wireless connection and convert to LAN network beside using computer /laptop at location B?

What are you trying to achieve? If the PC & Laptop at B are equipped with wireless NICs and can get a strong enough signal from the router at A to connect then what else are you after? Goin' Fishin' (Some day)

Yes its called a network bridge. Google wireless bridge. Guantanamo bay is a National Disgrace! End it NOW!

Also, there are some wireless routers which will work in "client mode", where they can be configured to use the WiFi signal for the WAN or Internet connection and route it to computers plugged into the Ethernet ports. You would configure such a router to use the router at location A to connect to the Internet. Thing is, there aren't very many wireless routers which do this. The Edimax BR-6204Wg does, but I can't find anyone selling them any more. It is actually just a software (or firmware) thing, the hardware in any wireless router can do this. This is one of the advantages to replacing the factory firmware with something like DD-WRT, which is a third party firmware that works on several different brands/models of wireless routers. The trouble is, if you attempt to do this and it fails during the attempt, the wireless router will be ruined and any factory warranties voided.