Hey guys, it's me again. I have several questions to ask. Just answer some questions that you guys feel like to answer, and leave the rest if you guys don't want to.

1. Is protein powder a necessity in your diet, or it's simply a convenience?

2. I asked this before in my previous post, but how to calculate your needed macronutrient and calorie intake?

3. Can you shape your body with only cardio? Somebody claimed that his body gets muscular and leaner with only rope jumping. I want to know if it is true.

4. Can back support item help me maintaining posture when doing exercises? Or I simply need to learn multiple times until I get it right?

5. Is there a useful book you want to recommend to gym rat beginners?