The FW800 model, and that model ONLY in G4 PowerMac, does have the internal slot for both and use both. Purchased a Bluetooth card from FastMac, do a Google, mine was on special at $29.00. Airport Extreme Cards are available for about $40.00. Make sure your Mac has both antenna leads fitted before outlaying cash.
The advantage over the dongle is wireless keyboard and mouse will perform so much better, no lost connection issues and even booting from disk which did require use of the wires keyboard and mouse.
Sleep is no problem with any key awakening.