OK, if you're on a router and connect to your router through DHCP, "ipconfig" and #4 give you your network IP, a "fake" IP address that's only good within your network. Your real Internet IP address is the one you get wehn clicking on link at #3.
If you don't have a router, they'll be identical, but if you have a router, they'll be different. So if you need to know your IP for online gaming purposes for example, you need your real Internet IP. Your network IP is useless unless you are just trying to connect to other computers on your network.
As for why the IP changes everytime you connect/disconnect your ADSL connection, that's normal. It depends on your ISP and how they have their DHCP configured. They probably have it set to give you a different IP every time. Some ISP's change your IP every day, others change it once a week, etc. The bottom line is that your IP is dynamic. Some ISP's have the option of having a permanent IP but you have to pay a lot more money for it.