Thank you Kentucky Todd!
Would you believe I have actually located three other people that might be crazy enough to attempt this with me in October and also own a 4WD vehicle?
The thought is to do a marathon shuttle - rendezvous at Portal (burger), drop a car, load into one car, drive another 6+ hours to the other side of the Sierras, camp near trailhead and head out on the HST the next day. (Finish at Portal, eat at least two burgers and an entire plate of fries, then hop in the car that was left behind and drive ALL THE WAY BACK to the other side.) Thought about doing the key-swapping technique, but I rather have more people around to eat if I get stuck in the wilderness and run out of food.
My greatest concerns coincide with your number 1 & 3. We'll be monitoring weather up until the day we leave, but I've been suprised by waking up to an unexpected 12" of fresh snow on Mt. Whitney at Trail Camp before and had to slog out in blizzard conditions after the weather reports said 30% chance of only 1-2 inches. Mt. Whitney is one thing, it was familiar territory so I just hiked down and surveyed land marks and was able to find my way out in white out conditions, but on the HST, snow half way through (3-4 days in), I won't be able to use the same logic.
I'm willing to bet Doug won't hike that far to come save me

I'd go during the summer, but I work for the government and my particular office forbids that much vacation at the end of the fiscal year (June-September).
Does anyone know where I can look up historical snowfall records for the HST areas?
Is there anyone out there that has done the HST in winter conditions and can offer any additional words of wisdom?
What are the trickiest points on the trail to navigate in slippery conditions?
Will we need rope or will crampons/ice axe be sufficient?
Opinions and warnings welcome.