Does immigration gets notified if a green card holder is detained for a major offense in Gretna, LA?

You need to contact an immigration lawyer along with a real good criminal lawyer to protect your interests. Immigration gets info only if police...

How long will it take for my wife and daughter to get their immigrant visa (Green Card) after I have petition for them?

I assume your family is overseas. At present, F2A is backlogged for all countries, it's taking aaround 2 years to complete the process from filing...

So far you have a letter from school about your volunteer/unpaid intern job, you will be fine.

N-400 Interview before ROC approval

Yes, they will conduct both interviews together. They will make sure that marriage is in good faith and you are living with your wife.

How long after receiving my Green Card can I start filing for my wife and daughter? How long does the process take?

If your wife and daughter are overseas, you can file any time. if they are in USA and came on visa, you need to wait until you become citizen.

Can I file for F1 student visa before the end of 6 years of after h1

Yes, you can file for student visa and i don't see any problem in getting it. If you convert H-1B to F-1 in USA, you won't be able to travel until...

Is it ok to stay in US on B1 visa, some weeks more (but within expected duration listed on I94) than official purpose of visa

You can get return ticket and explain it to CBP officer if he/she asks that you would like to travel after conference and you should have proof of...

Can i still continue to file my i130 petition for my wife even if i have an ongoing case?

It depends on the outcome of the case, you may file I-130 and get priority date.

Can we still expect to receive greencard being outside USA for more than 5 years?

If you have left the country after I-485 was filed and never requested AP or your employer filed I-824 for consular Processing, it will not work,...

A US LPR petitioned for an unmarried daughter who is not in an oversubscribed country. The Priority date is March 22nd 2010

It depends on the Priority date and when it becomes current. NVC will contact if approved I-130 file has been sent to NVC