Answer:

You can definitely do less cardio and increase your weight training for effective fat loss. In fact, in the long run, it'll be more effective because you'll keep more muscle. That means when you go off dieting, your body will be able to burn more calories and you'll be less likely to gain it back.

Doing cardio only burns calories while you're doing it - it doesn't build muscle.

I would suggest at least 3 times a week weights and 2 times a week cardio. With weights, you could feasibly skip shoulders but I wouldn't recommend skipping your back. That's where the biggest muscles of the upper body are and they're very important for posture.

If you don't work the back, you may end up getting a hunched posture and an unbalanced physique. Shoulders get worked with other movements and can be set aside for now safely.

I've got some fat loss articles on my site that I think will help:

10 Things You Can Do To Lose Fat Without Even Trying

Protein and Fat Loss

Why We Get Fat - Hunting Big Macs and Gathering French Fries

Nine Surefire Ways to Gain Fat

What Do You Mean Low-Intensity Training Isn't The Best For Fat Burning?

The Insider Secrets of Interval Training - Learn How Now

Fat Loss Circuit Training