No, a USB to serial adapter requires USB drivers, which grub just doesn't have.
Other options include:

• Installing a separate copy of linux as the a 2nd option in grub. GRUB can be configured to change its default boot option before booting. Then configure your first linux copy to set the grub default back to its self after networking is up and running.
• Enable network booting in your bios, and configure another computer to act as a BOOTP server to serve a copy of grub and a configuration file.
• Some motherboards which might not have a serial port on the backpane will still have a serial port header on the motherboard. Its just a matter of getting an adapter.

Yeah, I like the feel of the apple keyboards, but I use Linux, and I don't like the scan code mappings.
It shouldn't be too hard to create an alternate layout which reports the expected key codes for the F1-F12 keys, remaps Fn to Insert, F13 and F14 to Print Screen/Sys Req (So I can use the magic Sys Req key when my computer crashes) and Pause/Break.
The remaining F15-F19 keys can be remapped for extra features.
Then the keyboard would be fully compatible with Linix and Windows machines without the need for special drivers.

The LCD on my EEEPC 1000he uses way less than 6-15w.
With linux, a stripped down window manager (awsome), screen at ~30% brightness and bluetooth, wifi, sd slot and webcam powered down, it idles at 8.1-8.3w. (I think the hdd is spun down at this point)
Turning the backlight off only gets me down to 7.9w, and If I put the screen at full brightness the entire power load only increases to ~9.2w.
Clearly the Screen isn't using the bulk of the power.

No matter where you define the origin, your going to have the same problems.
Everything is going to move, at different velocities in different directions, even the origin.
To find a planet you will need know:

1. Where it was at the time of origin
2. Relative to the point of origin at the time of origin,
3. How much time has passed since the time of origin,
4. The velocity/acceleration of the point of origin
5. The velocity/acceleration of planet.

This isn't hard for a computer to calculate. But you will never be able to locate a planet to just by a set of coordinates like you can do with GPS, you will also need to include a series of vectors regarding velocity and acceleration, which could get complex if you need describe complex orbits.

What happens when one of the packets actually gets corrupted?

Put a linux box between him and the internet and setup packet shaping.
Create a script that lets him play for so many hours, then slowly degrade the quality of the connection until he quits in frustration.
Start at 2am, and slowly move it back each day until he is only playing a few hours a day.

Your never going to get them to cooperate with you, so Instead just go along with them. Then think up some bogus excuse to find out what software is installed, and assume any software you haven't given them is pirated.

Then go to all the affected companies and buy the licences from them. Keep all the licences Locked up at the head office. Just leave the branch offices with the pirated software installed.
That way you have the moral high ground (and probably legal immunity), the companies get their money and the branch office doesn't get angry with you.

Finally, its about time.