Update.
Alright, so I took out my battery and put on a charger for the past 24 or so hours. Let it charge fully then tickle charge afterwards
(the Noco Genius 10 is an amazing device, btw 
). After it was done - I got about 13.6v on the multimeter, cool. I put in the car, and I'll be damned.. it started. It sputtered/struggled a bit, but hitting the throttle pushed it over. I'm just thankful I didn't have some serious EWS->DME issue.
However I'd like opinions on some voltage readings i've been getting while it was running (via Hidden Menu 9). These readings were all during idle also.
Idle | IHKA Off | Headlights Off - between 13.6v - 13.7v
Idle | IHKA On | Headlights Off - between 13.4v - 13.5v
Idle | IHKA on | Headlight On - between 13.1v - 13.3v
Off | 12.7 - 12.8
(on the battery)
Are these measurements indicative on an alternator prematurely going out? Some folks here report an average of 14v from the alternator - although I'm not sure if it's idle or under load. If so, I may have to start sourcing a used one from the junk yard.
My apologies for the pickiness/paranoia, I just really love my car. haha