I've heard that an hour of cardio 3 times/week is maintenance. If you want to drop weight, do more. I've also heard that cardio is about endurance, not intensity, for weight loss. I've tried HIIT in the past and had better results from longer, lower. Get a heart rate monitor and learn how to use it for your conditioning level.
As for lifting, during the first 6 months or so a circuit will work fine, doing two runs through a circuit every other day, 3 times/week. The machines at your gym will be fine - just get someone there t show you a decent circuit to follow doing sets of 15 reps for fat burning. I also think 30 minutes cardio before gets your heart rate up and also, believe it or not, gives you some energy to make it through the lifting routine. At least do 10-15 minutes before and then 15 after on your lifting days.
I'm not at my home computer to share a good heart rate chart but you can go to the Lifetime Fitness site (I no longer belong but the chart is great) and look for the PDF file that gives you heart rate zones. A second page will describe how to use the chart and determine your own zone which really has nothing to do with age like you might have heqrd previously. Thishould be the link:
lifetimefitness.com: Life Time Heart Rate Zone Chart
Good luck.