No worries for your missus here. Russians are not racists generally speaking, you guys will be fine in that regard.
There are overnight trains, luxury and high-speed trains that run between the 2 cities, though I am not sure which is which by now. I used to use the "Aurora" express, and it wasn't luxurious, but ok for the prices paid.
The ATMs there are all over the place, and besides the cirrus and plus system, I think some in the hotel districts are also accepting JCB, AMEX etc. I generally have one rule when using ATMs in Russia. First try to use an ATM downtown, in the hotel itself, or at the very least, in a protected enclosure. Sperbank's ATMs are quite ok (They are the most extensive bank in Russia), and some others like AlphaBank are also ok. Just avoid those weird machines sitting in the middle of nowhere from a bank that no one seems to know of. I have also used ATMs located at supermarkets like Ramstor, and so far so good. Don't worry, all should be well in Russia!
