No, you do not need to register with the selective service if you entered the US after age 28.

What to do

You should consider hiring a competent traffic defense attorney.

Can filling extension to Mother-in-law visa impact Green Card process?

You should definitely apply. Just ensure to include evidence that she plans to return. Consider hiring an immigration attorney to assist you.

Can i change employer while i 485 pending with my current H1b sponsor?

I agree with the previous responses. Your I-140 and I485 must be more than 6 months old, in order to transfer to a new employer.

Can F1 Student open C Corp and receive income that earned via approved CPT ?

No, you can only work for your CPT employer. Talk to your school's DSO

Can I work with an expired H4 EAD?

No you cannot. You have to apply for an EAD extension.

If a conditional green card holder becomes a joint sponsor, does it affect his future LPR processing?

Won't be an issue, as long as you have a strong I-751 case, like Mr. Esparza has rightfully said.

No, not if you're telling the truth.

Depends on your lease agreement and if there were damages to the gate.

Depends on what the crime is. Consider a private consultation with an experienced immigration attorney to review your criminal records.