1. I don't recommend SharkBites for permanent installations. Search here, you will see many of the same opinion.

2. I don't think you will get much water out with a vacuum. You might take the valve apart (i.e. unscrew the top portion) and may get a little more water out.

I'm in the North East, I've purchased foam covers for the outside spigots. Google "outdoor spigot covers for winter freeze protection"