High RPM low gear

Background info:
I came into custody of a used 2009 Pontiac Vibe GT less than 24 hours ago and I'm afraid I've undone the previous owners immaculate care. I knew very little about the car other than it wad very well taken care of and the price was right due to the 300,000+ miles on it. My first experience with it was the 50 mile drive home through a raging blizzard that had me white knuckling the steering wheel with eyes wide, barely blinking as I barreled through the half foot of snow doing its best to hide the highway. Since I had just filled the gas tank and I was obviously traveling well below the speed limit, I didn't really even look at the dash other than when the flashing traction control light prompted me to glance down. It was a rough ride as you can imagine and I had the radio on quite loud for stress-control. Thanks to these contributing factors, I never realized until I saw that I had somehow used almost half a tank of gas in only 50 miles, that I had accidentally shifted into S (manual shift mode) instead of D and was likely in first gear for the entire drive at speeds up to 60 mph. I am positive I've done damage but which parts and to what extent I couldn't say. The poor car might have even been giving all sorts of signs that I was in about to take first place in the Guinness book of blonde moments. However, in those weather conditions I never considered that the extra heavy foot necessary to keep moving forward had any other cause than driving against a 30 mph wind in snow that at points came up to my door panels and thanks to the surprisingly enjoyable sound system I never heard a peep besides Elvis Radio on XM.

Advice needed:
There's probably nothing but time that could answer my most pressing questions now such as. How bad is it? And, how lucky am I to have made it home at all? (A lot lucky, methinks) And why does it force an automatic downshift in manual mode when the rpm's drop but it won't shift up or jump to neutral when you are going two times a gears recommended maximum speed and (I assume) practically redlining for the majority of an hour?

My questions for you, I hope are easier to answer. Which parts in this case would you expect to have taken the most damage? Do you recommend anything that I could or should do immediately that might aid my vehicle's recovery from this beating? Could the excessive revving have caused damage to anything that might present with a sudden drop in gas mileage? (Because just warming it up in idle for twenty minutes seems to have eaten nearly 1/8 tank) And last, what signs/symptoms should I be on the lookout for that would indicate a worst case scenario after this event?
After asking my local mechanic friends and getting all of the obvious cookie-cutter responses, any advice besides "don't do that again" or "hope for the best, but prepare for the worst" that you can offer is appreciated more than I can express. Thank you!