Replying to Fitness

Hey guys.
Im finally at a point with my new job that I can no focus on getting back into shape. My previous job left me with a lot of unhealthy habits that Im starting to get rid of. I havent been able to ski in the past 3 seasons due to career growth opportunities. I am completely aware Im not in the slightest shape to go skiing and that is why I am asking for your help. Im finally at the point in my life where I can settle down and look forward to a ski season.

Like Ive said, Ive been cutting down on a lot of unhealthy habits. Ive completely eliminated soda from my diet and have been only drinking water or milk. I also have not been eating out as much as well as avoiding the fast food.

This past week Ive been going for jogs/walks followed by some gym training. Ive been using an app called "Full Fitness" to help build workouts. I have a few questions relating to slimming down as well as toning my body, and before you say it. Yes I know. Diet is crucial to this and Ive been working on it.

Should I split my focus on cardio and weight training or priortize one or or the other?
Is it beneficial at all for me to be using any sort of supplements/vitamins when training?
How sore is too sore?

Any help is always appreciated. Help a fellow skier out.