She can file an application for a tourist visa, however it can be difficult for a single Russian woman to prove she is eligible. You cannot file a fiancé visa for her until and unless you have met in person. Your best bet is to go to Russia and meet her, and decide if you want to get married then and there, or to wait and file a fiancé visa.
The above is intended only as general information, and does not constitute legal advice. You must speak with an attorney to discuss your individual case.
There are significant differences between the B1/B2 and the K1 visas given your situation. If you petition the woman as a fiancee, K1, you will have no choice but to marry her within 90 days or she will be in the United States illegally. The B1/B2 visa will allow her to come to the states as a visitor and if it works out between teh two of you, you can always get married. Of course, there are consequences if she overstays with a B1/B2 and doesn't marry a United States Citizen. I highly suggest that you contact an attorney for more detailed information.
Once the US consulate discovers she has a significant other in the US she will be denied a visitor visa. If she lies and does not disclose that she as a significant other here she will be lying to immigration, and this carries very harsh penalties.
Normally in circumstances like this you need to visit your significant other in a 3rd country or in their home country. If you decide to marry you will then use a k-1 visa to bring her here or you can marry outside the US and file a marriage consular processing petition.
See below for a link to more information on the K-1 visa...
Representing clients throughout the US and around the world: www.PogueImmigrationLaw.com (513) 549-4420. We cannot provide legal advice or recommendations unless you retain our law firm to represent you. No attorney/client relationship will begin until you sign a representation agreement and make a retainer payment to open a case with us. Any information found here is general in nature and should not be relied upon in individual cases.