Yes, you can have multiple black belts in different martial arts. In theory there are no limits to how many black belts you can earn. As long as you become good enough to qualify for a belt in each fighting discipline, you can earn another belt with any others you might have.
All black belt practitioners can fight but not to the same extent. If the black belt is earned as a symbol of excellence, it’s fair to say that he or she can really fight. If the black belt is earned for mere competence, then he or she have achieved a certain level of mastery but may or may not ‘really’ fight.
Martial arts in and of themselves are not haram. It is fairly easy to adapt martial arts to be halal. However, some aspects in competitive martial arts, such as hitting the opponent’s face and causing bodily harm, should be considered haram.
Martial arts are practiced barefoot because going barefoot indoors is common in Asia, it improves your ability to train your foot posture and your muscles, and it improves the way you feel and perceive your surroundings.
There are Kung Fu masters in MMA but due to the nature of MMA fights, it may mean that you rarely see them practicing Kung Fu in the MMA ring.
You can spar with training gloves. Both sparring gloves and training gloves protect your opponent but training gloves also give more protection to your hands. This means that sparring in training gloves provides less real-world training than sparring in sparring gloves, which are meant to mimic real fights as closely as possible.
No, professional fighters do not have to register their hands as weapons. However, things aren’t quite as cut and dried as they might appear. A professional fighter’s hands may still be considered deadly weapons in court, even if they aren’t required to register them.
It is fair to say that unless you want to be a professional martial artist who competes at an international level, you are never too late or too old to learn martial arts. You can be too old to become a professional but if you want to do martial arts for fun, weight loss, exercise, or self-defense, age does not matter.
Not only can a fat person learn martial arts, but there are many good reasons to do so. Martial arts boost self-esteem, reduce anxiety and depression, and they reduce the risk of diabetes, cancer and heart disease.