Almost no equipment. You can train anytime anywhere. No restrictions and limits. Calisthenics provides opportunity for creativity. You can make almost any movement pattern extremely hard and intense. IT’S FUN. It gives you the opportunity to learn control over your body. Calisthenics gives you lifetime opportunities to train and get stronger and you’ll depend on nothing but your bodyweight and your determination. Most importantly a HUGE benefit that blows away any other training is its sustainability , ability to build real-world strength and ability to build mental toughness.
I don’t sit and count calories but I am very aware of what my body needs to maintain, grow and repair, so I base my eating habits depending on my schedule and training habits. Because of the intense training that I do I make sure I take in as much complex carbohydrates and quality protein source foods as I can.
The majority of my meals comes from Lentils, quinoa, beans, broccoli, spinach, whole grain breads, pastas and cereals, wild yams, brown rice, almond milk, nuts, fruits, peanut butter, mushrooms and supplement with some protein powder; to name  a few…
I’ve been training since 2006 , eight years now. I started with weight-lifting the first four years then transitioned to mostly bodyweight training in 2010. 
Yes I do, although supplements should just be that that to supplement your existing meal plan. I do take protein post workout and drink amino acids and creatine during training as well. 
I typically stay lean year round as a result of my training but for the most part it lingers from 4% – 6 %

Core and the basics, mastering them to the point where I dominated the exercises. From there I started putting together bodyweight workouts circuits that helped me progress into more challenging exercises.

(I have my training programs available in the Workouts menu)

Yes , as long as you give your body the proper rest (sleep) and nutrition for proper recovery.  You can follow a successful calisthenics routine that can give you exceptional results. In my opinion however, it is best to take at least 1 or 2 days rest.
The good rule of thumb is to progress further when you have mastered the current skill and it feels easy. I know that sounds a bit vague, but in reality everybody will have different numbers. Some people will be able to hold a position for 5 seconds and progress further, while others may need to hold it for 15. Remember that you must not be in hurry or you will fail. Make the resistance progressive and you will be get closer to your goal.