Purchasing school uniforms is easy and needs less hesitation and consideration. No matter what the school's policy is, there are only specific essential  pieces to the wardrobe that are necessary, so it won't break the bank. A few wardrobe items can last a long time. Parents could also enjoy an easy morning, as it will take less time to choose a set of clothes for the school day.

上面是摘自一篇关于校服的文章，阅读到黑体文字部分no matter what the school's policy is,there are only specific essential pieces to the wardrobe that are necessary遇到以下疑问求教：

1.specific essential pieces是指什么？是指items of the school's policy on dressing还是指items of school uniform ?

2. wardrobe在这里是指衣柜还是指学生的校服？

3.介词短语to the wardobe怎样理解和翻译？语法作用是什么？

4.定语从句that are necessary修饰什么？

谢谢老师！