my wife is in Russia and I already appied for immigration visa filing I-130. K-3 was disigned to reduce waiting time so your spouse is able to come to the States before his or hers immigrant petition is approved. You just gave me same stuff that I've read in instructions. Did you read those items? Then could you please tell me what documents I need? Thanks
Yes, that was the purpose of the K-3 visa when it was created. At that time, "the immigrant petition" was taking 24-36 MONTHS to be approved, so there was a great need to have this bridge visa.
Currently, the immigrant petition I-130 takes about 6 months to approve.
Currently, the K-3 process takes the same/nearly the same amount of time as the Immigrant Visa, but with far less benefit and much greater expense.
By the time you get your receipt from the I-130 and the docs ready for the I129f, you might find that your I-130 is well on its way on its own. You can check processing time estimates at uscis.gov and search the net for others who have filed around the same time as you for more reality-based estimates.
The K-3 is not a requirement; your wife might be to the US just as fast with a better visa if you leave it alone.
You should really be certain this is the path you want and understand how it works.
The instructions are clear on what to include; you just need to go through the instructions very carefully. Here is one guide that might help you get organized:
K3 Visa - Guide to Filing the I-129F Fiance(e) Petition