Is my alternator kaput?

Last night, I got a battery warning light on my cluster. I was on the road, so I stopped to run my errand, then got back in the car and paired my OBDeleven. Battery read 12.5V with the engine off. I turned the engine back on and let the light come back on, and the battery read 11.8V.
So at that point, I figured I may have a failing alternator and I'd have a trip to the junkyard this weekend to hopefully find a donor CC/Jetta/Passat.

So this morning, fired up and went to work. No hesitation starting, no slow starts. Battery light is still on during my drive. Same story when I started the car to come home. However, when I was about 5 minutes from home, multiple other lights started coming on: ABS, traction control, EPC, and airbag all came on. Then, about 40 seconds from my driveway, the power steering light came on yellow, then quickly switched to red and I lost all power steering. Barely managed to get the car into the garage (engine is running/idling totally fine at this point).
So once I'm in the garage I leave the car on and pop in the reader; the battery is at 9.7V under load. I lock the car and the horn beeps perhaps 30% as loud as it usually does.

Can a bad alternator, leading to a loss of overall voltage, cause all of this? This is my first new-ish car with oodles of electronics (coming from a '95 Celica), so this sort of near-catastrophic electronic failure is completely new to me.
Will a working alternator solve all of this? Or are these symptoms uncommon for that failure point and should I take it somewhere?

Alternative question: how can I be sure if the issue is the alternator itself, or perhaps the voltage regulator?

Yes a bad alt will cause all that and more.... The entire car is run by electricity so without proper voltage you don't go.

Replace alt. Charge battery. Go forth and sin no more against the charging system gods.

GeorgiaBII said:

Yes a bad alt will cause all that and more.... The entire car is run by electricity so without proper voltage you don't go.

Replace alt. Charge battery. Go forth and sin no more against the charging system gods.

Click to expand...

The gods were angry that day, my friends - like an old man trying to send back soup in a deli.

Thanks for your response. I was certain it was the alternator last night, but all this drama today made me second guess myself.
Would you say it's pretty likely that it's just the regulator?

You have 2 options.

1. replace the alt with a preferably new or re-manufactured unit or used unit.

2. remove alt and have it tested and repaired.

Guessing just costs extra money. Either test or replace the entire assembly.

I think I will try to get lucky at the junkyard and check to see if I can find any good alternators, then have it tested after I buy it. At worst, it's a $35 gamble.
I have the aforementioned Celica to lean on for a few days.