You’ll need a flash for indoor pics. Once it gets cold and ice crystals hang in the air, flashes don’t work so well. They have a tendency to light up the snow in front of the lens and block everything else. My trick to get around that is to set the camera on the bulb setting for a multi second exposure and use a flashlight off to the side to light up the subject. Incandescent flashlights give a nice warm color to the subject. Slave flashes or first flashes on a long cord work as well.
During the daylight time period you will need a fill flash. Your camera will try to darken the snow and in the process the subject will darken as well. A flash that goes off even when not needed will allow the snow to be dark but will light up who ever you want to take a photo of.
The long telephoto is good. In the winter a photo that was first taken by Clark a few years ago is now the sought after photo on station. It’s the moon passing behind the cross on OB hill. Everyone tries to take it, few succeed. You need a long telephoto lens.