Well now, given that 2 days ago we had the coldest day here in 112 years @ -43C (-50+ with windhchill) and we're still stuck in the deep freeze, I feel qualified to offer my opinions on the OP.
I've had no issues starting my Stinger during this cold snap. I finally used the block heater for the first time the night the it dropped past -40 but prior to that I've been able to use my UVO app to remote start it at temps down past -35C with no issue . Also, there has been no noticeable difference in the steering either.
As I posted in the Interesting Discoveries thread, I did find out that, with the hood ajar to allow a block heater cord to plug in, the UVO remote start won't function. I may look for a way to run the block heater cord through the grille at some point, but it's not a huge deal.
The HVAC system has worked very well up until these last couple mornings of legit -40 temperatures. What I've found is that at these extreme cold temps, I've had to keep the HVAC set to full defrost speed at a high fan setting in order to keep all the windows clear. I normally use the setting that splits the venting between feet and defrost, but over the past days I've found that the side windows will start to fog up some if not on full defrost. Also, when just idling in traffic, the heat being produced is nowhere near as warm as when travelling at speed, or as warm as it normally would be at idle. But I'll chalk that up to being really, really f*cking cold out.
Overall, I've found the Stinger to be a very capable winter vehicle. The only changes I've made for winter was an adjustment of my Custom Setting (the drive mode that I typically drive in) by changing the AWD split from Sport to Comfort and the addition of some really good Nokian winter tires on 18" rims.
I think the OP must simply have a bad battery. Not sure how to explain the steering problem.