Each experiment will have a state name as a codename. This will allow you to avoid accidentally signing up for multiple sessions of the same experiment. Sometimes the session will be scheduled directly with the experimenter. The body of the message will give some information about the experiment and who is running it. For privacy reasons, you will not be asked to post your phone number or student number but may be asked to send them, or other information, directly to the experimenter.
Sessions lasting longer than an hour are worth one credit per hour or portion thereof.
I will try to make sure there will be sufficient research opportunities during the term to fulfill the requirement, I cannot guarantee you will be able to do so if you wait till the last moment. You can cancel up to 24 hours ahead of time by posting a reply to this effect to your initial sign-up note, thus notifying your classmates that the slot is open. The penalty will be waived only for documented emergencies. You can always cancel without penalty as long as you show up to the session. You won't get credit though unless you make a good faith effort to try out the experiment.