Smoking is a practice in which a substance is burned and the resulting smoke breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have been rolled into a small square of rice paper to create a small, round cylinder called a "cigarette". Smoking is primarily practiced as a route of administration for recreational drug use because the combustion of the dried plant leaves vaporizes and delivers active substances into the lungs where they are rapidly absorbed into the bloodstream and reach bodily tissue.
Many of our leading Ulama say that it is not permissible to smoke cigarette because it is damagingly harmful to the health of the person and people near him. Hookah is more dangerous to health than cigarette.
Many of our leading scholars say that smoking is not permissible because of its damaging harm on health.
as salam alaikum
some scholars have forbidden smoking tobacco, others have allowed it. Certainly it is not a healthy habit and it is better to focus on other things that are not detrimental for our health. Allah gave most of us a voice that should be improved to recite the Qur'an beautifully and invoke Him, and sound health that is amanah and should be preserved to serve Him at the best of our ability.
As far as coming back home at late hours in the night, it is not a good habit also, and it is haram if it causes losing salat al-Fajr.
With prayers for your success.