1. I hope you are working on EAD and you have Valid H1B sticker in your passport
If that is correct then you have to use AP because you have used EAD for work, if EAD is not used you can enter with valid H1Visa sticker
2. Your wife and son :if they have valid H4 in the passport and have not used EAD for work in US they can enter on H4 visa, if they have used EAD for work in US then they have to use AP, they have to reach US before AP expires
3 if your wife and son are out of US and not going to use AP then they can stay out and no limit, if they have filed I-485 with you and used EAD then they have to enter before AP expires and will use AP. If have valid H4 Visa sticker in the passport and have not used EAD in US they should enter any time before H4 visa in the passport expires. No limit of time to stay out of US for your wife and son. Your lawyer is wrong or your questions are not clear.
4 if you have used EAD , you will enter on AP before AP expiry date
5 even if you have used EAD and your spouse and son have not used EAD for work they should enter on valid H4 visa, if have valid AP and H4 expired then they can enter on AP before the AP expires. No such limit of 1 month or 2 month.