I'm running Ubuntu Gutsy on a Dell 1501 right now. :D
Everything works pretty well. You should connect it with a network cable after booting and run the restricted drivers manager to install the wireless card driver. Pretty much everything else works right out of the box.
There are a few...
Yep, you can rename it to whatever you want without breaking it. My grub menu has 2 linux kernels and "Windows Vista Super Home Business Platinum Pirate Edition 2000%".
One reason is that system calls are really, really slow. Just like you wouldn't want to cache data on the hard drive, you would want to avoid functions with system calls for operations that require speed.
Q. Can you sell a proprietary copy of a Linux kernel.
A. No. No you can't. The GPL License was specifically made to prevent that kind of shenanigans. You might want to check out the BSD-licensed BSD kernels, though. Apple did precisely what you are asking about with the BSD Mach kernel.
Q...