Suicide is a major sin in Islam. Prophet Muhammad stated that the one who commits suicide will be punished with what he used to kill himself. Suicide is not disbelief that puts a person beyond the pale of Islam, as some people think. Rather it is a major sin that is subject to the Will of Allah on the Day of Resurrection: if He Wills, He will forgive it, and if He Wills He will punish for it. The Prophet refrained from offering the funeral prayer for one who had committed suicide, as a punishment to him and so as to deter others from doing the same. But he allowed people to offer the funeral prayer for him, so it is Sunnah for the people of knowledge and virtue not to offer the funeral prayer for one who has committed suicide.

It is proven that Prophet Muhammad forbade a man to travel alone in several Hadiths. The prohibition to travel alone applies to the one who travels alone via empty and remote routes. If there is no risk of being lost, and where there are likely to be helpers and companions, there is no wrong with travelling alone.

The point is that whether we say that the hadith of Umm Salamah is sound or not, it is not recommended (mustahabb) to single out the festivals of the disbelievers for fasting; rather it is disliked (makruh) to do that. Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said: It is not permissible to single out the festival days of the polytheists for fasting. End quote from al-Fatawa al-Kubra (5/378). An exception to that may be made for Saturdays and Sundays, according to those scholars who think that the hadith of Umm Salamah is sahih, as noted above.

Prophet Muhammad commanded us to close the doors at night and mention the name of Allah whilst closing them, when night begins, when going to sleep. That is so that the Muslim may protect his house and his family from any harmful devil coming in, whether from among mankind or the jinn, and also from harmful animals or insects coming in.

There is nothing wrong with you killing snakes that are outside the house. As for those that are found inside the house, they should not be killed until they have been warned for three days.