I've been talking to a Russian woman and she and want her to come visit. Can I buy the plane ticket here or only send her $$ for ticket only

You should be very careful about sending money to a foreign national overseas. There are a lot of Romance scams taking place internationally, so you should talk to an immigration lawyer about the steps necessary to have somebody come here on a visitors visa. Additionally, you should discuss with an immigration attorney any conversations between she and you to see if what she's telling you conflicts with any immigration laws currently in force.