OPT & I-94 expire on 9/30 while H1b is still pending?

Dear all, I have some urgent questions as follow.

I'm working on OPT right now, and applied for new H1b on 4/9, but so far it's still under "initial review". If I didn't receive a decision by 9/30, 

1. Can I legally stay for its pending status while I-94 expired? 

2. If I can stay, is it necessary to extend I-94 for an "official record" ? 

3. If I got a denial result for H1b after 10/1, do I have a 60-day grace period (for opt) from 9/30 or the date of the denial decision? 

I do appreciate it if somebody can answer these questions. Really anxious during these waiting days.