Two excellent questions!

The pattern for weight training depends on what your objectives are. Generally, training happens almost daily, but on successive days different muscle groups are exercised (e.g. upper body on day 1, lower body on day 2, upper body on day 1, etc.). Starting out at a "reasonable" workload (amount of weight, number of repetitions, speed of movement, etc.) and progressing at a slow rate is the safest way to go. Most beginning weight lifters start out too hard, too fast and develop muscle and tendon injury, which then becomes discouraging for them. Don't make that mistake. I often advise people to carefully decide what they want to do to start and, after they tell me what they want to do, advise them to start at about 1/3 of that intensity. Whether you use low weight, many reps at speed or heavier weight with few reps slowly depends on whether you're trying to build functional capacity/power or muscle bulk. Don't neglect aerobic conditioning (brisk walking, cycling, etc.) which is necessary for the success of a weight training program.

In terms of diet, a well-balanced diet adequate in calories is best. Special supplements and chemicals are not necessary. Moderate calorie restriction coupled with weight training will tend to reduce fat and build muscle, so your weight may not change a great deal. Remember that if you are imposing a weight training/aerobic program on your body, your caloric needs will rise, and so you'll probably need to take in more food. Watch the scale (occasionally, not every day) and observe your body's configuration to guide you as your program continues.

Good luck with your program.