Dead alternator could/would explain your dead battery....
My 2005's original battery shows 12.4v when left overnight
13.4 to 13.9 when charging/running along the highway (varies with speed/load (lights,etc))
Drops to 11.smidge during the starting cranking (i pre-start the ScanGauge to have the VLT showing before turning the key)
For reference, i have the 115 Amp alternator.
Is the alternator hard to replace?
There are a number of threads discussing it (with photos).
One quirk is that there's a *slight* asymmetry to the alternator housing that requires it be placed with a Vee-notch against the engine. If you get it in "upside down", you can't fully tighten the belt.
ALL posters agree: buy a real Bosch alternator, not a 3rd party "equivalent".
(also, the broken part could be the over-running clutch in the alternator's pulley, or the mounted-on-back diode and regulator assembly, not necessarily the alternator itself)
--dick