You can view an open MRI here: http://www.webmd.com/brain/open-magnetic-resonance-imaging-mri-machine. The time varies from 15 to 90 minutes depending on location and type of scan. You can ask your doctor or radiologist...
No, it will just work, assuming the SIM is valid (like the account has not been blocked, etc.); if the phone is locked you will get a message that the...