Xiaobaitu, please help again about H1b

Xiaobaitu, I asked last time about using EAD (based on 485 pending), then applied for H1b next year.

I just found it is very tricky. If I applied H1b next April outside US, which will start to be effective Oct 1, 2007. Can I use this H1b to enter US in April? It seems to be too early for a job starts at oct.

And if I can come back in April on this new applied H1b, can I still work with previous EAD until Septermber 30, then switch to H1b?

Too many questions, Thanks a lot!