H1 B 6 year expiration question

My I40, 485 and EAD is pending and I am Dependent. My H1b will be expired in next February, 12. I had to stop to work next February.

However, my company lawyer said I can take unpaid leave after my H1B expired, until I get the EAD card and back to work. (BTW, Company has agreed to keep my position).

My question is:

1) Am I legal to take unpaid leave with AOS status? has anyone heard this before? Will it impact my GC process?
2) I am planning to apply H4 first, look like it is not necessary any more, am I right?

Please advice me. Many Thanks!!