Stick with OEM spec.
50/50 anti-freeze Distilled water/antifreeze, Oil 10W-40 or 0/5W-30/40/50, synthetic. I personally like 5W-30. Then 10W-40 rest of the year (when I lived in Flagstaff where is is below 32˚F most days in Winter)
Whatever you choose or can get.
I use distilled water and vinegar in my washer fluid tank.
Watch out for freezing lock mechanism's as well. I had mine freeze up a couple times and had to enter through the rear door.
Not sure what you can do for this?
I am sure there is more you can do. Hope that helps?