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Question: Dodge Caliber, No Start Troubleshooting

Ok, I've gotten tons of answers lurking on this site in the past but finally need to seek help actively.

I have a 2007 Caliber, SE, 2.0 L

I have a no-start scenario that has evolved a bit over the last 24 hours.

Last night:
car would crank and then stall/die after about 3 seconds of running
slight smell of oil the first time and the oil light comes on
After 3 occurrences of this, the car stopped turning over at all, at this point the CEL light came on for the first time in forever. also electrical light comes on, no more oil light

This morning:
Get a read on CEL: P0522. Oil Pressure sensor it says.
I check oil and I'm just a millimeter below the "safe" zone, assume i have a leak and here is a few drips below. full disclosure I'm about 800 miles over due oil change.
Put more oil in, now in the "safe" zone, still no start
Next time i tried, car won't even turn over, classic low battery symptoms.
Bring around another car for a jump, get the car back into its attempts to start.
Disconnect jumping car and back to low battery like conditions: clicking, no turn over, all the lights and wipers go crazy when trying to start car.

So that's where I am now, a few other tidbits
Battery is ~2 years old
New Alternator, about 9 months old
I did need a jump about 4 days ago, wife left AC on while engine was off..


So my questions are:
Is my problem the Oil Pressure Sensor like the OBD indicates?
Is it worth trying to replace the battery