You can rely on the validity of the Bible. It began hundreds of years before the written word, but the people were careful to not change it. That is part of the reason why there is not a lot of detail in Genesis. By Exodus there was the written word.
The Bible is the first book, but it was kept in manuscripts in the beginning. There are more identical copies of the Bible's manuscripts than any other book in history. There are more than 5,700 manuscripts of the new testament in Greek alone. That means with all the languages there are about 25,000 manuscripts of the new testament in the ancient languages.
There are many translations of the Bible, but throughout history it was God's people who copied it word by word, line by line to make sure it was not altered. Today, some dialects have strayed from the exact truth, but NASB has stayed very close grammatically to the Hebrew and Greek. To copy the thought process into English the NLT is one of the best translated Bibles to understand the meaning and concepts of the ancient languages. Bible Gateway and YouVersion are good apps of the Bible to use.
The chapters and verses were added to make it easier to find context. It began to be used in 1557 when the English Bible was being printed. None of this takes or adds to God's truth. It is about making your personal Bible Study easier.
Psalm 12, 19:7-11, Isaiah 40:6-8, John 17:13-19, 2 Timothy 3:14-17, & 2 Peter 1:19-21