Should I bring friends?

Absolutely. We have found in the past that if people attend in groups (e.g., if a whole lab's worth of students show up together), then everyone gets more out of the training. People who sign up together are more likely to have similar interests and backgrounds, and are usually less inhibited about asking questions, and asking one another for help, than total strangers. Plus, it's a great opportunity to wear that departmental t-shirt that's sitting in your drawer ...