How do you bring ingredients to room temperature when its winter?
As long as you have the heat on in your house, it shouldn't be an issue really. But for butter and eggs, here are some answers: 


Microwave the butter for a few seconds to soften it up; put the eggs in warm water until they come up to temperature.
Room temperature for butter just means relatively soft (spreadable, like it is when you don't refrigerate it). For eggs it just means not cold.
Not sure what the recipe is, but, as I just mentioned, room temperature butter is more malleable than cold butter. Eggs fluff better when they're warm (e.g. its more difficult to get peaks when whipping eggs if they're cold).