USB port is for a LAN Adapter $20-$25. I have it but my speeds are the same pretty much.
If you have Opera Internet Browser go to speedtest.net. It will automatically recognize the wii and you can check the speed.
Updates? They come every few months so it shouldn't affect you much.
Also you can use a USB keyboard there are 2 USB slots.
If you cant move the router closer- make sure it is up high and your wii should not be on the floor. Stand it on its side not flat. Try to remove any barriers between the router and wii. Especially metal.