“Tithing, the Canon, and the Christian Mind”

1. I’ve heard people use 2 Corinthians 8, specifically verse 8, to say that tithing to the church is voluntary, and not a requirement for believers. How do we biblically support the belief that tithing is a necessary part of a Christian’s life?

2. How did we get our 66 canonized books of the Bible? Other religions, like Catholics, have 74 I think. What criteria, method, and who determined the 66?

3. If the Bible alone is the word of God, why is it ok or even encouraged to read other books or learn from other sources?