I answer your questions, not because they have not been answered correctly, but to reafirm what has allready been said,
I would like to start with the question
Do you honestly believe that joseph Smith was a prophet of God and Saw him?
I answer that with this question, HAVE YOU READ THE BOOK OF MORMON AND FOLLOWED MORONI'S COUNSEL, if not than it does not matter what anybody else tells you, You see you have to have your own personal experiences, you have to have your own conversion, and without that you will just be another inactive on the churchs membership list, and we don't sit idly and let you be inactive, but its immpossible to be active without a testimony and the question i posed you is the most simple and fundamental thing in the church, because IF YOU FIND FOR YOURSELF THAT THE BOOK OF MORMON IS TRUE(AND IT IS) THEN JOSEPH SMITH IS AND WAS A TRUE PROPHET OF GOD AND EVERYTHING SINCE IS TRUE AND THE CHURCH OF JESUS CHRIST OF LATTER DAY SAINTS IS THE ONLY CHURCH ON EARTH THAT CONTAINS THE FULNESS OF THE GOSPEL, its that easy,
now back to question # 1 about the undergarment, it is a reminder of covenants made in the temple,
#2 it is not your responcibility, or mine, or anybody's here on earth at this time to be able to fully answer and understand that question, it is a calling from God, just like being called to teach sunday school, or to go on a mission, if the lord asks us to do something he will provide a way, and it is my belief that i donot have to understand polygamy because i will not be called in this life to do so. as well we will have a full understanding in the hereafter and that still does not mean you will be involved in polygamy, but sorry for rambling the good news is you do not have to worry about it.
# 3 i allready answered yes, and yes
#4 I will not look at those site, i do not involve myself in anti, or in others opinions, if i have a question or need counsel i will work that out with my bishop. not on a website. however i can tell you that it is completely against church policy to involve yourself in things that would seem socially taboo and sex is a wonderfull thing IS NOT TO BE PERFORMED WITH THE HOLY GARMENT ON, AND is still fun. not just for making babys,
#5 contrary to what you may have heard or believe, some of the most intelligent people in the world are LDS, and i do not follow blindly, however that said, you must sustain and support our leaders, but you will know if they are out of line, and if so you may report that to there superior.