a) Can't. How can I, a human, explain something as unfathomable as God. It's faith.
b) After Jesus ascended into heaven, God or Jesus rarely spoke to humans. I believe, that to be still the case. Jesus briefly conversed with Acts. Jesus gave a few short commands in Revelations. If memory serves me correct, I believe that's it, outside of the first 4 gospels.
c) Like many ancient manuscripts, the Bible is orally communicated stories of events, that at some point was finally written down.
d) Continued moronic view that Heaven is a place of pleasures. Answering that other guys bullet point.
I tried to answer your questions as straight forward as possible. Please allow me to elaborate.
A) If God were made up, I can give you a wide variety of proofs that God exists. Especially when I take some Percocet and turn on Pink Floyd, I bet I can provide some imaginative proofs. But since God is real, I can't. It does take a leap of faith. Because I can't speak with you, I have to assume, you believe in evolution. I'll just deal the creation part. What proof is there that the big-bang theory is true or that when, much like Jupiter or Saturn (or others) today, back then on earth, there were only rocks, fire, chemicals and elements. Then suddenly, out of no life whatsoever, something living appeared. We keep looking for water and/or life on Mars. Seriously folks, just add water and poof, you get life. Is it that easy? When you see how complex and wonderful living organisms are, you have to ponder the possibility of God. To believe or not, that's up to you.
B) I think this was answered sufficiently.
C) There are many ancient texts, probably the same, communicated orally, then written down. Yet the Bible is dismissed most highly. Other ancient manuals will be looked upon as maybe a good source of history at least, excluding the supernatural stuff. But many today, don't even see the historical influence the Bible has had on many archeological diggs today. How do you know some tribal or village script or scroll is true or accurate? Maybe they were fictional stories in themselves. But how many archeologists do you know, when they find a manual, wonder if it's accurate or not. None. They regard is historical fact. The Bible is the word of God, people back then heard, and passed on generation to generation.
Many Christians focus on death and resurrection of Jesus Christ, and rightly so. But many others also make the teachings of Christ, and the Bible in it's entirety, as some sort of lovey dovey book. No, the Bible is a book of God trying to bring back His created people to Himself. Much like a mother trying to bring back their child from self destruction. And most of the Bible is about how people continue to fail to go to God and believe, trust, obey Him. With the single highlight of how Jesus died for our sins on the cross, be resurrected to provide a way to save us.
Why would people write a book like the Bible, filled with constant failures of people, people like in the land of Ur during Cains time, Sodom and Gomorah, those following Mose in the desert, King David's shortcomings, 18 out 26 kings thereafter who didn't follow God, wars, famines, plagues. To highlight the bright spots of those were obedient to God, crying out to Him, acknowledging Him, and to demonstrate of Christ's sacrificing love, and the work He did to save us.
And that's the difference in the Bible and other texts. We don't do the work of saving or going to heaven. God has done it already. When you find a religion that offers how you can get yourself to heaven, I'd be weary of it. What will be the standard? Will it be graded on a curve? What are the criterias? This leaves way too much room for subjectivity and confusion (something that the denominations of Christiantiy do as well. There should only be one "Christianity" under Jesus Christ). A religion based on our ability to get there, that is wrong. Why should you get to heaven and not me... I think I was better here or there? Those are the questions that will be raised.
When you look at the life of Christ and how He lived, and not other Christians, there's no question He lived a perfect life, a life worth investigating.
I cannot change you. There is no hope in me that you will become a Christian, if you're not one already. I hope that my words will challenge you to read the Bible, maybe starting with the New Testament, Gospel of Mark (it's short). Only in the word of God is there hope.