基本上可以通用

In my understanding, "莽撞" is worse than "鲁莽". 莽撞："莽" means "鲁莽" hot-headed, rude and impetuous. "撞" means "冲撞人" as a result to offend or to provoke someone. I would say 鲁莽的年轻人 or 莽撞的年轻人 鲁莽的态度 but not 莽撞的态度 I hope it makes sense to you:)

可以的