Several Router problems

It sounds like an ADSL signal strength issue. Test that it is not a problem with the ADSL phone cable setup, using the shortest ADSL/Phone cable you can find (under 1Meter is best)unplug all other phone line using devices and filters from the wall jack points and test the routers connection again as the only device plugged in(this is Isolation testing) If the issue replicates itself under isolation testing conditions then ring your ISP providor and request that the "ADSL signal voltage" needs to be increased slightly as your router is not hearing the ADSL signal properly. If the issue doesn't replicate itself under isolation test conditions, you are either using an old or bad ADSL/Phone cable or your cable is too long (should not be longer than 5meters)or if you are using a wall socket/splitter for direct adsl access (without filters)then test the socket with a filter to verify the socket/splitter is not the cause of the problem, if you do use phone filters, during isolation testing, test each of the filters individualy with the router and see if the disconnection issue is replicated if so replace the bad filter the disconnection issue was being caused by phone signal interferance. Your third request requires you to setup the LAN info on the windows side of your connection not the wireless card, this can be verified by searching for websites via thier IP address which will work, when searching via their website name wont, DNS resolution issue, it is probably best practice to use MAC Addressing for your wireless setup though.