In the course of life, we are ineluctably facing many choices which may dramatically change our life and lead us to different paths to the future.（face一般跟problem搭配,跟choice,也可以；引到不同的道路上介词应该用to,而不是on；后面to the future是我添上去的,使句子显得更加饱满）.
It's a different thing for 16-year-old teenagers to make decisions which have something to do with their near future, such as whether going to the college or working in a company after graduating from high school. (你的句子太过繁琐,而且易犯错误.表达意思是对的,但其间偏离了正确的英语表达方式.例如“beginning to decide going to college, working after high school”这个表达很没有必要,working是不及物动词,后面最好加个地方什么的).
However, for Amish teenagers, age 16 is a turning point in their life- they are facing a harder life choice whether they should join the Amish church or not. (这里的冠词应该用a而不是the,决定是否应该如教堂用should会比would更贴切).
Those Amish teenagers in the film “Devil’s Playground” make their choice very differently; （这里的问题不大）.
some would join the church and permanently live a Amish lifestyle, while some would choose to leave the Amish community and continuously explore the “English world”. （live...lifestyle,不需要介词 in；另外,用while比and更好,显出两者的比较）.
Yet whatever decision they made, it will definitely drift them to different directions. (这里用and显得很突兀,不好,我建议用but或however或yet；另外,用drift in是错的,用drift to会好一些).
In addtion, that either decision they made will inevitably leads them into a new pathway of life along with both advantages and disadvantages. (改为In addtion可使行文更加流畅；后面的基本没问题）.
改好了哦,不知道你认不认同.另外说明一下,我是大二的英语专业生（下学期就大三了）,知识面还是蛮广的（请谅解,没有显摆的意思）.