These questions are best answered through study of The Perfect Matrimony by Samael Aun Weor. See the referenced link below. However, I have written a short response to each of your questions.

1. Most human beings have, unfortunately, indulged in the orgasm throughout their life. However, this does not mean such persons cannot change spiritually if they are sincere. What it takes is complete renunciation of such animal behaviors and the adoption of the esoteric practices of White Tantra (sexual connection without orgasm, lust, or fornication).

2. It is possible to reproduce children through scientific chastity: sexual union without orgasm, in accordance with the law of karma and the will of the Holy Spirit.

3. One must never reach the orgasm in their life. Never. Period. To do so occasionally is only to deepen suffering and fall into further degenerated practices, represented by Gray Tantra (occasional orgasm). This is the Greek myth of Sisyphus, who raised the stone of sex up the mountain only to let it drop again, thereby repeating a horrible mechanical cycle of suffering. This indicates a person who transmutes occasionally and orgasms occasionally. Such persons are not serious.