Green cards for my family : immigration

Hello,

Before everything I’m very confused so please don’t roast me too onerous.I’m a 25 yo US citizen who lives overseas. My dad and mom and sister (19yo in august) aren’t US residents.I hold trying stuff up and the I-130 type the is the one factor that hold developing. Each article retains giving me completely different varieties in addition to that one. My dad and mom are divorced.From what I gathered every of them must file an I-130 and the entire course of for every can take 1.5 years.My questions are the next:

-What number of varieties do they every have to fill in addition to the I-130? This web site says reveals a complete of 5 varieties. Altho I haven’t been capable of finding a web site that reveals the identical data as the subsequent.

-When one in every of my dad and mom get the inexperienced card how lengthy will it take for them to present my underage sister one? What if she’s 21 by then how lengthy would that take?

-I perceive I must be residing in the US to present my dad and mom a inexperienced card however during which a part of the method does that must be the case? Which type would require me proving that?

-From the websites I regarded up the whole value of giving a father or mother a inexperienced card would vary from 850 to 1900 which obtained me confused. How a lot wouldn’t it value for one father or mother? How about my sister?

Sorry for the lengthy put up.