It depends on whether you like research or not//1。在公司能做到高位的,通常都在美国有过硕士,博士的经验
Don't think it's true.
//2。以本地的学历,中国人的身份,没有美国的学历很难收到提拔
Somewhat true, but generally I have not seen Chinese occupying high positions in Singapore. So it is unclear whether you'll be promoted even with US degree.
//3。我念完博士还年轻,进公司做几年科研完全有可能转去其他部门
Everything is possible, but why do PhD in the first place if you want to jump to non-R&D dept?
3rd question is very good!