After some time, I just started working out since i decided to get in a very good shape... I'm 191cm and 86/87kgs. That weight is about right for me but i need to replace my fat with muscles... I droped around 10kgs in a past few months with a rigorous workout and diet. Now I'm burning aroud 700kcal a day with cardio and lifting weights moderately. Also, I'm making a daily calorie deficit around 500kcal by watching my nutrition. The progress is just satifying but i worried that i will lose muscle by training so hard.
My question is... How can i lose fat and build muscle simultaniously? Is it bad that i lift weights and do cardio in a same day? Should I base my nutriorion more on protein?

Other question.. It's been a while since i've been runing in nature due to very high temperatures outside and I've been using a threadmill. The question is, is running on threadmill more easy than ordinary running, better, the same or what?

And another one.. I have a pretty good build but my fat is stored in my lower belly, buttocks and obliques.. I know i need cardio training to get rid of that fat, but will doing more excercise on that particular muscle groups help me get rid of it, or just strenghten the muscle below fat... Eg. If i do more situps for my lower abs, will i get the result or i need to enhance my cardio?

Thank you for your answers!

1. Its not bad to do cardio and weights same day, many dont do it because they dont want to be in the gym for 2 hours or so. You could try to split cardio days and weight training days depending on how many days you have.
Base your diet around 40/30/30 or something similar with the 40 percent being protein.

2. I prefer running outside just because of the fresh air, but the treadmill is not bad either. Its good because the belt is moving and can help you maintain a higher pace (IMO).

3. You cant reduce body fat in certain areas, otherwise everyone would be flabby with six packs. Concentrate on your larger muscle groups and on losing total body fat. Abs are just one muscle, not six.