You need learn a lot from this forum

他们会不会就不给我H1b的工作机会呀.

It depends on your boss. Normally, they should apply H1b for you.

有人说用了OPT，我的绿卡申请自动作废，是不是呀？
No. It is opposite. After you I-485, your OPT has no chance to be approved.

你的意思是，申请到H1b得职位后，在四月申请H1b，十月可以
收到H1b visa.在五月和十月之间，我可以用EAD领薪水工作，对吗？谢谢。

If it is a profit company, the beginning date can only be Oct 1. Since the quota is always used up in May, you should apply H1 in April. During the H1b pending period, you can only work with EAD. Otherwise, the company can not employ you legally. If you are lucky(i.e. I-485 is not denied before Oct 1), go outside US to activate your H1.