We don’t have recent numbers as to percentage of young men serving a full-time teaching mission. However, in 1991 a survey was done, which found that 32 percent of young men serve two 2-year teaching missions.
While there is no official doctrine on reading books from other faith traditions, members of The Church of Jesus Christ of Latter-day Saints have long been encouraged to seek out learning as a lifetime effort, this often includes reading things beyond our own canonized scriptures or the modern words of our Prophet, Apostles and other Church Leaders.
There are probably as many answers to that question as there are people who have been excommunicated from The Church of Jesus Christ of Latter-day Saints.
Mormons believe that “God is no respecter of persons” (Acts 10:34). He loves all of his children, regardless of when or where they were born. We also believe that baptism, and the covenants we make at baptism, are stepping stones on the path to salvation and exaltation.