Enter US using VWP while visa application is under AP/221G

[smallox]

We(my wife/my son/myself) received 221g after L1/L2 visa interview.

Since this year AP is taking longer time, My wife is considering to enter US using VMP first.
Background:
1) We are Australia Citizen, and we are renewing L1 visa. No history of denial.
2) My son's L2 visa expires on 9/10/2017, My wife's expired in July/2017. They are planning to enter in late Aug/2017.
3) I will wait for visa issuance from overseas.

My question is:
a) Can my wife enter US using VMP while waiting for 221g clearance?
b) Can my son(9 years old) enter US using existing L2 visa(expirs on Sep/10/2017) while waiting for 221g clearance? Can my son stay after 9/11/2017
c) can they enter US together using VMP and L2 separately?
d) Is flight ticket for my wife mandatory to convince custom for VMP? if yes, she can book one ways ticket to Canada first. Once new visa is issued, she can reenter using renewed L2 visa from Canada.

Thanks heaps for your answers in advance.

[smallox]

can someone please shed light on this?

[inadmissible]

Do you already have ESTA Travel Authorization? If not you should apply for it. It will be valid until your visa application is rejected

That said, there are never any guarantees you will be granted admission at the port of entry despite having valid ESTA TA, or even a visa for that matter. Unlike an L visa, admission on VWP requires overcoming the presumption of immigrant intent. Your wife & son would need to present a credible travel plan that is temporary in nature