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You may need to take out some of the woods. Over time trees and shrubs, as well as other plantings, can outgrow their surroundings. A landscape makeover may be necessary.

Ground is considered frozen if it's tamperature is less than 0*C and ice crystals are present. Ideally, plant material located in frozen ground will either have limited moisture requirements and/or have adequate moisture provided prior to the ground's freezing. Hope this helps.

It depends on the type of shrub and how much of a snow load it's carrying.
If the shrub is bent by the weight of snow to "an uncomfortable" angle for an extended time, some shrubs may not be able to recover their shape. A snow load does act as insulation against temperatures (to a degree) and wind, which often does more harm than temperatures.
I find this a difficult question to answer because there are many factors to consider: Is the shrub bent to the breaking point? Is more snow expected before existing snow can melt? How flexible is the plant? Is it safe to be out removing snow?
I have been quilty of making the excuse of getting snow off shrubs to get out of the house and playing in it, only to find broken stems and minor branches from beeing too enthusastic in snow removal. Over the years, I have found a happy medium by gently taking some of the snow load off shrubs that I felt were being weighed down too much, but leaving enough to be of some insulation use.

Yes. Depending on your zone, you should have many options of heat loving plants, Just make sure that what you choose is hardy in your Zone. (USDA hardiness zone)

If you are looking for ways to protect your plants from cold weather or freezing, these articles may help: https://www.gardeningknowhow.com/plant-problems/environmental/protect-plants-in-freeze.htm, https://www.gardeningknowhow.com/plant-problems/environmental/protecting-plants-winter.htm Row covers and cold frames help as well: https://www.gardeningknowhow.com/garden-how-to/projects/building-cold-frames.htm, https://www.gardeningknowhow.com/edible/vegetables/vgen/row-covers-for-garden-plants.htm

Actually, the USDA just updated their gardening zones. This map will show you the latest gardening zones based on climate change data: http://planthardiness.ars.usda.gov/PHZMWeb/# For more info on your particular growing zone, this link should help: https://www.gardeningknowhow.com/planting-zones/minnesota-planting-zones.htm