It really depends what kind of router you have. Each manufacturer puts it somewhere else, but usually the selection of the standard you want to use is under Wireless Settings. Your router should have Mode selection there.
As a manufacturer default, your router will be set to Mix mode of B, G and N, so any wireless card which uses one of the following standards will work without any setting changes.
Without knowing what router you have , I can only offer an example by providing you with info how to change router mode on Dlink DIR-655 router
Open Dlink Emulator
http://support.dlink.com/Emulators/dir655/132NA/login.html
Click Log In
Click on Setup (top row)
Click Wireless Settings
Click Manual Wireless Network Setup (button)
and now you will see "802.11 Mode" setting on the screen, where you can select mode B, G, N or mixed
Yes, almost every n-router available supports b and g-modes too.
If the network uses the RIP protocol, router A will determine that all paths have equal cost. If the network uses the RIP protocol, router A will update only the A-C-E path in its routing table. If the network uses the EIGRP routing protocol, router A will determine that path A-D-E has the lowest cost. If both RIP and EIGRP protocols are configured on router A, the router will use the route information that is learned by the RIP routing protocol.
router#config t router(config)#router eigrp 100 #net NETWORK ADDRESS
ICMP
SIPR Or SIPRNet stands for Secret (or Secure) Internet Protocol Router Network. It refers to a Wide Area Network Utilized by the Dept. Of Defense for Classified data transfer between known trusted entities NIPR or NIPRnet: Unclassified but Sensitive Internet Protocol Router Network Non-Secure Internet Protocol Router Network Non-Classified Internet Protocol Router Network
RIP is a routing protocol - a protocol (set of rules) that allows a router to exchange information, with other routers, about existing routes.
HDLC
This may indicate a duplex mismatch between two devices. e.g. a switch and a router. Change both to use auto, instead of hardcoding either half, or full
VOIP= Voice Over Internet Protocol
TFTP.
from 1 through 3
No, they are not the same. A router can connect several Ethernet networks together. Ethernet is the name of a layer 2 protocol.