1.After reading the chapter 8-10 in breaking dawn,do you think Edward is stupid to share Bella with Jacob just to save her life?

No not really...it was just another way of Edward proving how much he loves Bella.

It sounds absolutely ridiculous but Edward loves her so much that he would do it, which is amazing, cause he obviously wouldn't like Jacob so much since Bella love/ed him and wanted to give her to him just to save her life.