回复：正在DIY NIW，恳请有经验的大人进来一下，有问题请教。谢谢

1 petition letter 需要签名吗？如果签自己的名字的话，petition letter是用第三人称写的，会不会奇怪？
Yes. It is not strange.

2 论证requiring laber certification would adversely affect American interest的时候，是不是最好mention一下there is no labor shortage in the field? 如果是的话，要通过什么证明no labor shortage呢？
It is not necessary for this part.

3 是装订的问题，我想把所以的材料订在一起，那是不是140表上也可以打两个洞，然后用一个binder订在一起呢？

You can surely punch two hole on the top of your I-140 form and bind them together. But not with a binder. You need to use paper fastening.