First off, don't believe rumors, usually they are just speculations by people who don't understand the system. The most important piece of advice would be to do everything by the books, she should pay her taxes properly, work only 20 hours a week on campus if that is all her visa allows her and so on.
Basically the USCIS starts from the assumption that you have a legit marriage.
Go to the USCIS website for the most accurate information, but basically she will not need a new visa, she will apply for a temporary green card once you get married. Once the application is filed, her legal status extends automatically by 6 months. That is plenty of time to get the temp green card which is good for two years. After the two years are up, she will apply for a permanent green card (actually expires every 10 years but it's easy to renew). Finally after 3 years of permanent green card she can apply for citizenship.