Should I file I-130 for my child who came to US in jun 14 on B-2 visit visa. I am a PR and got my Green card in july 14

Yes you can file. Not eligible for AOS anyway. Also, he should go back home before his status expires.

I'm getting divorced, but my soon-to-be ex is willing to provide an affidavit for the I-751 the the marriage was in good faith.

Include as many bona fides as possible and yes, that letter from your ex should be helpful.

Is it possible to expedite my I539 CoS to F1 on the grounds of loosing full scholarship if F1 is not obtained by start of term

No specific form for expedited 539 (unlike the premium processing option for H-1Bs and I-140s). That said still make an expedited request on your...

Can my son remain in the US whilst I-130 petition is pending?

A pending I-130 doesn’t give the beneficiary status.

Is this possible? Please, can someone throw light on this for me, am confused.

How can your I-130 be approved when you did not file an I-130?

Does not going to school make my status hard to be approved?

Could be an issue, and you have to explain and convince the officer of your reasons why you did not maintain your F-1 status.

The employer (and or attorney) should’ve gotten it by now.

My Canadian wife and I (US citizen) just got married in MIchigan. Can she apply for SSN before she gets her green card?

If she gets her work permit she can already get ss.

Will it make a difference if I have my petty theft record expunged before marriage green card interview?

Expunged records are still seen by CIS. So the record must not make you inadmissible for you to get a green card.

I am a permanent resident in the United States (Green Card Holder)-my son is currently in the US (legally on B2)

You can petition but he has to maintain non-immigrant status and wait many years while doing so before he can adjust. A petition in itself doesn’t...