I'll answer each question one by one. 
 
- Personally, I’ve always been overly rational and pragmatic and, to be honest, I don’t think I would have ever even considered believing if I wasn’t born into a family who believed. Despite my skepticism, I eventually (as an adult) decided to analyze it with an open mind and it turned out that it (1) made logical sense and (2) I received a spiritual confirmation of the veracity of the restored Gospel. 
- Although I’m ashamed to admit it, my passion does ebb and flow. I find that the number one thing that makes it flow is serving others. 
- See answer to first question. 
- I have no idea why God chose the 1800s. One thing I do know, however, is that no nation had ever existed on earth that granted as much religious freedom as the USA did at that time. Joseph Smith wasn’t the only person at that time who felt that Christianity needed a “rebirth;” that was actually a fairly common belief amongst American Christians before Joseph went to the grove to pray. 
- Why would God suddenly become mute just because His communications that we have compiled in the Bible were recorded? Around the same time that the Church of Jesus Christ of Latter Day Saints was being founded, one of the greatest American thinkers, Ralph W. Emerson wrote the following in his book called ‘Nature:’ 
“The foregoing generations beheld God and nature face to face; we, through their eyes. Why should not we also enjoy an original relation to the universe? Why should not we have a poetry and philosophy of insight and not of tradition, and a religion by revelation to us, and not the history of theirs?” 
“We are now so far from the road to truth, that religious teachers dispute and hate each other, and speculative men are esteemed unsound and frivolous. But to a sound judgment, the most abstract truth is the most practical. Whenever a true theory appears, it will be its own evidence. Its test is, that it will explain all phenomena. Now many are thought not only unexplained but inexplicable; as language, sleep, madness, dreams, beasts, sex.” 
Emerson recognized that it was irrational to believe that God would speak to ancient generations and not to current generations. As Christians, we often criticize the Jews for rejecting the New Testament yet isn’t accepting only the Bible as scripture doing the exact same thing but with a later cutoff point? The God I believe in knows me and knows what problems I face today and wants to give me guidance through Prophets. He also knew the ancient inhabitants of the western hemisphere and wanted to give them guidance and send Prophets to them.  
- I believe these things are true because, as Emerson philosophized should be the case, I can find (and have found) answers to every question in the restored Gospel of Jesus Christ.

Those are very good questions. My first suggestion is to contact a friend you may know that is a member of the Church of Jesus Christ of Latter-day Saints, or to contact the missionaries. I say this because it will obviously be easier to communicate with someone in person to help you understand some of your questions, and to clarify what is being said. I would also refer to you mormon.org which will also help answer some of your questions. 
 
With that said, I would love to offer a few thoughts that might help, and to share my personal convictions and why I believe the way I do.  
 
Conviction or testimony comes most effectively through the Holy Ghost. This will most often be an assurance God will give us of truths as we act upon righteous principles that He has taught. We believe the Bible to be a valuable source of such teachings. I remember one of the first times I gained a conviction of the Bible, as I began to seriously study it when I was about 15 or 16. I received confirmation that it was God's word through the Holy Ghost. It came as a clear impression to my mind and heart that what I was reading was true, and it filled me with joy and happiness. As I have tried to live according to the principles taught in the Bible my faith has been confirmed that it is true. It is just as the Savior taught His apostles: "But the comforter, which is the Holy Ghost, Whom the Father will send in My name, He shall teach you all things, and bring all things to your remembrance whatsoever I have said unto you." John 14:26  
 
Later Christ confirmed Peter's declaration of testimony that Jesus was the Christ by saying that it was not flesh and blood that had revealed this to him, but His Father which is in Heaven. (Matthew 16).  
 
I have found the same to be true for my convictions of the Book of Mormon. I have read it seriously, with the intent to know if it is from God. As one of its prophet writers promised: If ye shall ask with a sincere heart, with real intent, having faith in Christ, God will manifest the truth of it unto you by the power of the HOly Ghost. I have received this witness. As I have applied the teachings of the Book of Mormon into my life, I have come closer to Christ, and have been a happier person. 
 
To me the God of the Bible and of the Book of Mormon are the same God. In fact, Jesus Christ Himself visited the people of the Book of Mormon in America as a witness that He is the God of all the earth, not just those in Jerusalem. This is a powerful witness to me of the far reaching love of God. He loves His children so much that He was willing to give His word not only to those in Jerusalem, but also to those who would listen in ancient America. 
 
I believe the Bible to be true, but I also recognize that there is no end to the word of God, and if He chooses to share His word with others, than I am in no way authorized to tell God that He can't speak any more just because of what has been recorded already in the Bible.  
 
I know that God lives. I know that His Son Jesus Christ lives. I love them. I know they love me infinitely. I trust that He is still ever watchful over His children on the earth. The greatest manifestation of that love was that God sent His Only Begotten Son into the world to die for our sins. In order to teach His children about His Son, Jesus Christ, God has sent prophets and apostles to teach His word. I believe He has done just that again in our day and age. It is a blessing to hear God's word through living prophets and apostles alongside the word that was preached anciently in the Bible. I am grateful to have so many strong witnesses along side the Bible that strengthen my faith that Jesus Christ is the Savior.  
 
If you would like to figure this out, I invite you to sincerely ask God if there is truth in the Book of Mormon. Pray in the name of Jesus Christ (as the Savior instucted us to in the Bible) and I know God will answer your prayers. Read from the Book and ask if it is the word of God. I know you will get an answer. Thankyou for asking so kindly on this website. Now ask God in faith. :) 
 
I hope this is somewhat helpful for you. Feel free to contact me or this site again if you have other questions.  
 
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