Green Card Process for my sister, her husband and children

[santy]

Hi:

I am a US citizen and i want to file for my blood related sister; once if I file for her will her husband and two children come with her automatically?

Does her children have to remain unmarried at the time?

How long usually does the green card processing takes? I heard from my friend that it would only take 12 years, is this true?

Finally, my sister and family plans to visit USA, and will it be easy to get a visiting visa for them, as they live in nigeria? Will this affect the filing of the Green card?

Let me know...

[immihelp]

1. Yes.
2. Yes.
3. 13 to 14 years.
4. They will not be able to get visitor visa while their green card is pending.