when should I do cardio and how much....

1st topic about cardio is...just because you are moving does not mean you are doing anything!!
You need to be in your target heart rate zone for your goals...if it is fat loss get in your fat loss zone which is lower than aerobic zone!

Aerobic Zone is for individuals who want to improve cardiovascular or training for a sport!

Trying to decide if you should hire a personal trainer?

Trying to decide if you should hire a personal trainer?
On the contrary, personal trainers are often very knowledgeable and can be instrumental in your overall exercise plan. A personal trainer can help you design a workout. He/she can work with you regularly — at home or at a health club — motivating you through each workout.

Consider hiring a personal trainer if you:

• want to reach a specific goal
• want to update your exercise program
  
• need motivation
  
• have been inactive and feel out of shape
  
• want to back through a plateau

A qualified trainer can assess your baseline level of fitness, set goals based on that assessment, and motivate you to adhere to the program so you can reach those goals.