Someone should pick up the first... and someone should figure out how to hook your GBA through the USB port for multi-player online gaming.
As for the second, If it can be done with a flash cart, I'd be willing to bet it could be done with some kinda of pass-thru/lock-on (Super GameBoy-esque) cartridge with a GB/GBC emulator on it. Granted, it'd probably suck complete and total ass, but Intec or MadCatz should be able to do something like this.