I have a few questions which I am very confused about:
1. Is it true that the lines on our hands change every 30 days or something like that? Do they even change at all? Some say it is proven from the Qur’an.
2. If one starts to recite the Qur’an from a middle of Surah and not from it's beginning is it necessary to say ‘Bismillah’ or is ‘Auzubillah’ enough?
3. If someone comes to a Masjid late and joins the Jamaat in the second Rak’ah, then will he recite Tashahud or not because in the end it will be 3 Tashahududs when only two are recited in a normal Salah?
4. Do we make and change our own destiny? I mean isn't everything that will happen already written in a book? Or as we do it, it gets written in a book? If it is already written somewhere then is it possible to change it through Du’a or does it change at all?
I really need to know. Please answer my questions.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

We do not know whether the lines of hands change or not.  It seems that the lines do not change because if a person takes a copy of his fingerprints and after some years he makes another copy of his fingerprints he will not find any difference between the two fingerprints.

According to our knowledge the matter is not mentioned in Qur'an.

We advise our brother not to waste his time in such silly matters since whether the fingerprints change or not, does not benefit you.

As for reciting Bismillahi Al Rahmani Al Rahim, if one starts the recitation of Qur'an from the middle of a Surah, should he recite Bismillah or should he recite only “A’audu Billahi Mina Al Shaytani Al Rajeem” (I seek refuge with Allah); the person has both choices.  He may recite A’audu Billah and Bismillah or he may recite only A’audu Billahi Mina Al Shaytani Al Rajeem.

As for the one who misses his first Rak’ah with Imam and joins the second Rak’ah, he has to follow the Imam in all his actions even in Tashahhud.  When the Imam finishes his prayer the person who missed the Rak’ah should continue his prayer and perform the missed Rak’ah. In this case, performing three Tashahhud does not harm the prayer since one is obliged to follow an Imam; thus the Tashahhud was a compulsory act for him when he was with the Imam.

As for change of destiny, it is reported that Allah has written the destiny of all His creatures fifty thousands years before their creation.

Abdullah bin Amr Ibn al-A’as said that the Prophet (Sallallahu Alaihi wa Sallam) said: "Allah ordained the measures (of quality) of the creation fifty thousand years before He created the heavens and the earth, as His Throne was upon water." [Muslim]

 Abudah bin al-Samit said: "I heard the Prophet (Sallallahu Alaihi wa Sallam) say: The first thing which Allah created was the Pen. He commanded it to write. It asked: What should I write? He said: Write the Decree (al-Qadr). So it wrote what had happened and what was going to happen up to eternity." (Abu Dawood)

Allah Says (interpretation of meaning): {No calamity befalls on the earth or in yourselves but is inscribed in the Book of Decrees (Al-Lauh Al-Mahfûz), before We bring it into existence. …}[57:22].

Allah has written all about His creation in al- Lawh al-Mahfooz (the preserved Tablet); this is called eternal Decree, which does not change.  There is another kind of destiny that is called contingent destiny, which is with the angels.  For example, the age of a person is thirty years in the record of angels and then he gives alms and thus Allah increases twenty years in his life and it is changed in the record, which is with the angels.  But what is written in al-Lawh al-Mahfooz does not change since Allah wrote that the person will give charity and his age will be fifty years.  It is not subject to changes.

Allah knows best.