What documents do I have to take at i485 interview ?

You should consult with an immigration attorney before you go to the interview so they can have more time to go over documents.

How many years can you keep renewing your green card without getting US citizenship?

You do not have to become a US Citizen. You can keep renewing every 10 years.

I submitted my documents to NVS how long it will take to get visa?

It will take 2-3 months. Also, it depends on the specific embassy.

Can I stay in US?

You need consult with an immigration attorney first so they can go over exactly what happened and whether you are able to stay here on that J-1...

Can i apply/get work visa while beeing outside USA and in proccess of i130 f4 green card?

You can apply for a work visa while your green card is pending, however, it is in conflict with the intent to immigrate which means you can be denied.

Due to a higher number of cases being filed, they are now sending cases to the field offices that are outside the usual range. Therefore, it is not...

How long case review time for nvc after you submit all documents?

You should give NVC about 30 days to respond. As far as the interview appointment, it is up to the consulate where you are at.

Is it okay if my affidavit of support paper is of different quality?

The quality of paper is not relevant.

Are you here in the US already? If you do not attend school, your visa is cancelled and you will have to get a new visa next year.

If you have a valid EAD card and are here in the US legally with status or pending application, you can travel domestically.