Again, EAD has no relevance as far as maintating status. The status is entirely governed by filed I-485. No-one is required to work... well, maybe except you, but that's because the GC is sponsored by your empoyment. Your dependants don't have to get or use EAD/AP, unless they would like to work or travel.
When your H1-B expires, you - and your depenants - become adjustees, which means that your status entirely depends on your I-485. If it is denied, you and your famility will have to leave the country immediately. From what I understand, the only reason to maintain H1-B when I-485 is filed is if you're worried that I-485 is denied. If that happens and you still have H1-B, you can stay in the US as a non-immigrant.
The choice of maintaining H1-B/L status when I-485 is pending entirely depends on your current situation and you should discuss it with your lawyer. Bot ways are legal, but confer different rights and have different outcomes if ( god forbid ) I-485 is denied.