On n-400 a question that asks “Have you ever been arrested, cited, or detained by any law enforcement officer for any reason?

You should mention ticket. and YES.

Stay on L1 B visa over 5 years if approved petition and Visa stamping dates are over 5 years.

Your qualifying time to stay in USA on an L-1B status is 5 years, not beyond.

What can i do ?

It is not an immigration related question unless you are F-1, and your concern is about maintaining you student status.

Mailing i-130 for parents

You can mail both in the same package but its better to put them separately in sub-envelopes.

I applied for N-400 in Houston, TX office through a lawyer? After the interview, does USCIS mail the oath letter to my attorney?

It is received in the attorney of record's office.

Went for interview on Jan 25 2018 and it went well, the officer said he would have approved it on the spot but my medical

May be a week or so, you should receive approval notice, and then permanent resident card.

You need to wait for the approval confirmation from USCIS for your pending request.

Can my dad get arrested if he was to come back from Vietnam on a vacation even though he completed his probation ?

You information provided is not complete. First question will be about his immigration status. If he will be returning as a non-immigrant, he...

Hello I have an approved VAWA from since 2005. I Can I file for my greencard even though I have been divorced since 2007?

Yes. You may file for Green Card. Being divorced, does not adversely effect your case.

I live in US with my wife and kids we are under pending court date for asylum application(pending removal)

The divorce decree must be final as per the US laws. If it is, your wife will not remain derivative beneficiary, but it will not effect children.