Need information for H1B to H4EAD conversion


I am completing my 6 years on H1B in Oct 2018 and I don’t have GC processing going on. I am planning to apply for H4 and H4EAD together as my spouse has I140 approved. I have few questions about this conversion:

Can I apply for H4 and H4 EAD together? Do I need to contact attorney or can I do it myself?

If DHS revokes H4EAD by then and if I get H4 approved before Oct 2018, do I need to stop working from the day I get my H4 approved? What is the best way so that I don’t miss the chance of working until Oct 2018 even if DHS revokes H4 EAD?

Thank you!