T.R.
Rats are great!! My husband & I got 2 rats a number of years ago, Daisy & Ella.
While they are in the same rodent family as mice, hamsters, gerbils, etc., rats tend to have a natural bite inhibition, making them easy to handle. And they love to be handled! Expect them to snuggle into your clothing (hoodies with the double-open front pocket make great traveling "slings" for them!)
Keep in mind, rats are very social creatures. Since you only have one, she will not only enjoy, but -need- to be handled daily. They are extremely smart, so training tricks for treats can be a great interaction.
We were advised against getting the clear exercise ball - rats have longer bodies & don't always feel comfortable in them. Instead, "rat proof" an area of your home that they can have loose turn-out in for exercise. To rat-proof cords, use the plastic tubing for aquarium hoses, slit it lengthwise & then tuck the cord inside.
We have large dogs, so this was not an option, but I know quite a few people who trained their rats to relieve themselves in the cage, & allowed them run of the house. Rats are naturally clean, & can be litter-box trained.
Be aware, not all bedding is safe for rats. No cedar - despite the great smell, the aromatic compounds it releases are actually toxic. Pine shavings are also coming under scrutiny. Aspen wood shavings are recommended. We actually used a recycled newspaper litter for cats, called Yesterday's News, worked great, & then made an area in the cage that was softer for snuggling into with a towel.
Chewing - rats will need to chew! Give them options - toilet & paper towel rolls are a good resource, also harder tubes from wrapping paper & oatmeal containers. Safe blocks of wood work well too.
Here's a link to some great resources of info for pet rats:
http://exoticpets.about.com/cs/careofrats/a/ratscare.htm
Have fun with your new family member! T. =-)