Cool. As for the Ethernet adapter thing, that is to hook directly into a router, am I right? Of course, a direct line is always better than a wireless connection, but if you have a router for your computers, will the Wii be compatible? And would it even by wise to use it from downstairs? Sorry - My experiences with Wireless technology have been less than reasuring.
On a slightly nerdy note (I have WAY too much free time in my first period class), I figured out a plausible way in which the Wii calculates the position, tilt, and roll of the Wiimote using the sensor bar.
The sensor bar knows the distance between the two sensors. Using this, and the angle at which the Wiimote is from each of these, it can use a "Angle Side Angle" canculation to find the X (the distance from the sensor bar), and from this, the Y (which would be the distance to the left or right of the sensor bar). It basically does the same thing to find the Z (height) coordinate, but it already knows the X (again, distance from sensor), and that the ground should be level.
So there you have it - You've triangulated a single point - the location of the Wiimote. But this isn't all that useful for pointing. It needs 2 points (using the same method) to find the tilt. The tilt would simply by the slope in 3-D space.
One last piece of information it needs is "Roll". To get "Roll", you need a plane - 3 points that aren't colinear. So by triangulating 3 points, you can then find the slope of a plane in 3D space, and with a couple minutes of calibration to customize the size of the TV screen and the position of the sensor bar in relation to your TV, you have some accurate measurements of the position, tilt, and roll of the Wiimote.