42. Was Srimad Bhagavad Gita actually recited by Lord Krishna in the battlefield or is it the imagination of the poet?

Yes. There is no doubt about the Gita having been recited by Lord Krishna in the battlefield. It is not a mere composition of Chiranjivi (eternally living) Vyasa. Recall to mind the following two Slokas which can be found in the Gita Mahatmya:

Gita Sugeeta Kartavya Kimanyaih Sastravistaraih
Ya Svayam Padmanabhasya Mukhapadmadvinissruta
Bharatamritasarvasvam Vishnorvaktradvinissrutam
Gitagangodakam Peetva Punarjanma Na Vidyate

The Gita is not a human composition at all. Have the conviction as such, without the usual questioning intellect. Remember all the Avatara Purushas like Sri Sankara and Sri Ramanuja who had written commentaries on the Gita. Lord Krishna Himself says to one of His lady-devotees named Lilabai that He and the Gita are identical and that worship of the one is adoration of the other. Study Slokas 68 to 71 of the Eighteenth Chapter of the Gita to infuse in yourself the necessary faith and love towards the holy scriptures.

43. Would you kindly suggest some effective methods for conversion and sublimation of the sexual energy into spiritual energy or Ojas?

Observe strict continence in thought, word and deed. Give up thinking useless and vain thoughts. Keep balance of mind in all conditions and circumstances, contemplating the Divine. Practice Sirshasan, Sarvangasan and Oordhva Padmasan, besides Viparitakarani Mudra. Preserve the energy by constantly repeating the Name of the Lord, doing intense Japa and meditation, and study of the Gita, the Bhagavata, the Ramayana and the like. Develop Viveka, Vairagya and Vichara. As dispassion increases, so is the vital energy not allowed to leak out. The greater the Vairagya (non-attachment to worldly objects) the more secure will be the semen. The more the preservation of semen, the greater will be the transmutation into Ojas which means abundant physical, mental, moral and spiritual strength and quick evolution. Pranayam helps a lot in gaining control over the physical machinery and the mind. To have control over the mind means to have control over the Prana Sakti and prevent Veerya from being let out. To have control over this masculine power means to have abundant Ojas which enables the aspirant to glow spiritually. Intense Sadhana, with the desires reduced to the barest minimum, will sublimate the sexual energy into spiritual energy. For further information, go through my book Practice of Brahmacharya. It gives exhaustive details regarding the subject in question.

44. Can truth be compromised in the sense that telling a lie is sometimes not only inevitable, but also indispensable? Will such a breaking away from truth be justified?

Truth is truth and falsehood is falsehood. They are as wide apart as the terminals of a diameter of a circle or the north and the south poles. He who wants ethical perfection, who loves Dharma for the sake of the Supreme, ought to stick to truth however crucial be the circumstances, however tense be the situation. Think of Harischandra ... how he stuck to truth even in the face of trials. How his name is to stand, for all time to come, for truth undimmed! Harischandra was truth personified. That is why he is known as Satya Harischandra. This single instance is enough to sustain man's living on a sound basis of truth, however disastrous and threatening be the crises one has to face. However inevitable and indispensable it be, and however much the situation demands to gain some selfish ends, falsehood should ruthlessly be avoided. Truth and falsehood cannot be linked together. Yoking of the one with the other is awfully absurd. No doubt, in the Bhagavata and other Puranas a few exceptional instances have been cited, where speaking untruth would be considered appropriate. But they are a matter of exception, they are not applicable to all times and all persons. For illuminating and interesting information in this connection, go through my book, "Ethical Teachings".