I got home yesterday evening and managed to spend the first night in almost a week in my own bed, which was lovely. This morning we had to buy groceries for the coming week, but the van was in the way and needed fuel anyway, so I asked Sabriena to put the Commodore out in the street while I fueled the van up, then I could back it all the way up the driveway when I got back, then we could go.
We did so (during which I successfully pissed a Colorado driver off sufficiently that he road-raged all the way through a red light), and then piled into the Commodore and when I turned the key... nothing. Pushed it back to the driveway and pulled the van down to jump start it.
It started fine after getting groceries (thought I was going to have to walk home to fetch the van), but I suspect the battery is likely on it's way out. I do also think that the power steering and intermittent electrical issues are caused by a slipping accessory drive belt, but the battery probably should have had sufficient juice to operate through that so I'll just bank on having to replace it.
It's on a charger at the moment, and Dad's bringing his battery tester out tonight when they come out to stay tonight.
Update: Tested the battery and the alternator, and it charges fine once it's been revved up, but won't charge immediately on start. Between this and the power steering issues, I'm suspecting the belt tensioner - it's booked in with the mechanic next week.