The main equipment needed to train for weightlifting is a barbell. A squat rack is helpful as one becomes stronger and uses heavier weights. Check this blog for more details
Weightlifting, like all Olympic sports, has a rulebook full of technical and procedural rules. Check your national governing body, or the Int'l Weightlifting Federation for current rules.
More correctly referred to as resistance training machines, there are many types available. Weightlifting is performed with barbells, or what is known as "free weights."
Yes, muscle mass (hypertrophy) can occur with free weights, body weight exercises, and resistance training machines.
A repetition continuum exists, so the number of repetitions used depends on one's goals. On one end of the continuum we have a maximum resistance, known as a 1RM (an intensity that prevents a second rep from being performed). This is the goal of a weightlifting competition. For most people, strength is gained by performing reps fewer than six. Training in the eight to 12 repetition range is generally associated with hypertrophy (muscular growth), as in bodybuilding. Training with 15 reps or more focus mostly on muscular endurance.