Finally got this figured out about a month ago, and wanted to drive on it for a while before I was positive.

Short answer - the Air Mass Meter did it.

Long answer - AMM was causing the engine to run really rich which in turn was flooding the cylinders with gasoline. So compression was minimal, which was the main cause of the no-start. Also, gasoline had made its way into the oil. I eventually had it towed to a reputable mechanic who flushed the oil, replaced the spark plugs and did some other things and got it to run, but it was still noticeably running rich and occasionally rather rough. I swapped in a spare junkyard AMM and, after a few seconds of idle speed jumping all around, it smoothed out and has run very well since.

Thanks everyone for all of your input. Such a simple problem with all sorts of misleading possibilities...