Medium intensity, and if you do it with empty glycogen stores, something like 30-45 minutes would be optimal.
Like Palomalo said, it is good to do your weight workout and cardio in the morning, since it kicks up your metabolism for the rest of the day, resulting in more calories being burned throughout the day, even when you're not doing any physical exercise.
Decrease the amount of carbs you eat towards the evening, and consume more fat, for example, fatty fish, penuts or even oil straight from the bottle (I get most of the fat in my diet this way, it's really convenient). Cold-pressed oils, such as virgin olive oil and flaxseed oil have the best fatty acid profiles, i.e. they are the most healthy for your heart and health in general. And, contrary to common belief, you actually NEED fat in your diet if you want to LOSE fat, since it slows the absorption of sugars and keeps your insulin levels steady (fluctuations in your insulin levels contribute to fat accumulation as well as the first stage of diabetes, insulin resistance, which can eventually lead to full blown insulin shutdown, otherwise known as type 2 diabetes).