I have my I-140 processed by my previous company. Do I need to initiate GC for my next H1 B extension ?

You should discuss this with your employers Immigration attorney

IF I aget an F grade in a semester, would I become ineligible to continue my CPT?

You need to address this question to your designated school official.

WHY DO THEY GIVE N-14 EVEN AFTER YOU PASS YOUR INTERVIEW

There may be additional questions as to eligibility beyond the application and testing.

You will not be eligible for naturalization while on probation. You should also have the criminal conviction reviewed by an immigration attorney if...

Is there a problem if I report employment details while on OPT to my college after 10 days?

You should address this question to your designated school official.

There is no set time in which biometric appointments are scheduled. 3 to 4 months is possible.

Can an F2 visa holder stay in USA even after his status is invalid and H1B is pending?

a timely file application for change of status is required to remain.

I 140 approval not received past receipt date in EB1

Wait until it is 30 days beyond the normal processing time

If chain immigration is eliminated by law, will pending or approved I-130's for parents still be honored?

Wait and see what if anything is passed

Do I need to file a change of status from H1B to B2?

As my colleagues have noted you have 60 days after H1B