From the Writings of Baha’u’llah:
Ye have been forbidden in the Book of God to engage in contention and conflict, to strike another, or to commit similar acts whereby hearts and souls may be saddened.
(Baha’u’llah: The Kitab-i-Aqdas, pp. 72-73)

To none is given the right to act in any manner that would run counter to the considered views of them who are in authority.
(Baha’u’llah: Gleanings, p. 241)

Ye are forbidden to commit adultery, sodomy and lechery.
(Baha’u’llah: A Chaste and Holy Life, p. 57)

Nothing whatever can, in this Day, inflict a greater harm upon this Cause than dissension and strife, contention, estrangement and apathy, among the loved ones of God.
(Baha’u’llah: Gleanings, p. 9)

He should not wish for others that which he doth not wish for himself, nor promise that which he doth not fulfil.
(Baha’u’llah: Gleanings, p. 266)

Lay not on any soul a load which ye would not wish to be laid upon you, and desire not for any one the things ye would not desire for yourselves.
(Baha’u’llah: Gleanings, p. 128)

…no man should enter the house of his friend save at his friend’s pleasure, nor lay hands upon his treasures nor prefer his own will to his friend’s, and in no wise seek an advantage over him.
(Baha’u’llah: Persian Hidden Words, p. 43)

It is unlawful to beg, and it is forbidden to give to him who beggeth.
(Baha’u’llah: The Kitab-i-Aqdas, p. 72)

Time and again have We admonished Our beloved ones to avoid, nay to flee from, anything whatsoever from which the odor of mischief can be detected.
(Baha’u’llah: Gleanings, p. 97)

From the Writings of `Abdu’l-Baha:
In this, the cycle of Almighty God, violence and force, constraint and oppression, are one and all condemned.
(`Abdu’l-Baha: Selections … `Abdu’l-Baha, p. 149)

From Letters Written on Behalf of Shoghi Effendi:
On no subject are the Baha’i teachings more emphatic than on the necessity to abstain from fault-finding and backbiting while being ever eager to discover and root out our own faults and overcome our own failings.
(Shoghi Effendi: Lights of Guidance, p. 88)

Concerning your question whether there are any legitimate forms of expression of the sex instinct outside of marriage; according to the Baha’i Teachings no sexual act can be considered lawful unless performed between lawfully married persons. Outside of marital life there can be no lawful or healthy use of the sex impulse.
(Shoghi Effendi: A Chaste and Holy Life, p. 56)

…[we] are forbidden to confess to any person, as do the Catholics to their priests, our sins and shortcomings, or to do so in public, as some religious sects do.
(Shoghi Effendi, quoted by the Universal House of Justice: Aqdas: Notes, p. 194)

From the Writings of the Universal House of Justice:
There are many references in the Baha’i Writings which prohibit the use of wine and other intoxicating drinks and which describe the deleterious effect of such intoxicants on the individual. In one of His Tablets, Baha’u’llah states:
“Beware lest ye exchange the Wine of God for your own
wine, for it will stupefy your minds, and turn your faces away
from the Countenance of God, the All-Glorious, the Peerless,
the Inaccessible. Approach it not, for it hath been forbidden unto
you by the behest of God, the Exalted, the Almighty.”

Abdu’l-Baha explains that the Aqdas prohibits “both light and strong drinks”, and He states that the reason for prohibiting the use of alcoholic drinks is because “alcohol leadeth the mind astray and causeth the weakening of the body”.
Shoghi Effendi, in letters written on his behalf, states that this prohibition includes not only the consumption of wine but of “everything that deranges the mind”, and he clarifies that the use of alcohol is permitted only when it constitutes part of a medical treatment which is implemented “under the advice of a competent and conscientious physician, who may have to prescribe it for the cure of some special ailment”.
(The Universal House of Justice: Aqdas: Notes, pp. 226-227)

Shoghi Effendi stated that one of the requirements for “a chaste and holy life” is “total abstinence … from opium, and from similar habit-forming drugs”. Heroin, hashish and other derivatives of cannabis such as marijuana, as well as hallucinogenic agents such as LSD, peyote and similar substances, are regarded as falling under this prohibition.
(The Universal House of Justice: Aqdas: Notes, p. 238)

From Letters Written by the Universal House of Justice:
Baha’i teachings on sexual morality centre on marriage and the family as the bedrock of the whole structure of human society and are designed to protect and strengthen that divine institution. Thus Baha’i law restricts permissible sexual intercourse to that between a man and the woman to whom he is married.
(The Universal House of Justice: Lights of Guidance, p. 367)