Nina - I did my nursing through UniSA (externally) and can answer some of your questions. You will need to go to Adelaide for workshops for every subject that has a clinical placement - they do a workshop shortly before the scheduled placement dates.
In regards to support for externals - you will be allocated a lecturer for each subject. Each subject has its own "webpage" and students are split into "discussion" groups (kind of like a tutorial group). You can email lecturers if you need anything although they also access the discussion groups (prferred method of contact).

A Grad Year is kind of like the nursing equivelant of a Doctor's Intern year. You work in a hospital (as part of a recognised Graduate Program) giving you the chance to consolidate your knowledge and clinical skills (whilst being paid for it) but recieving support, clinical guidance, and clinical education on the job. You can get information about it from the websites of most hospitals - go to the hospital website and search Graduate Nurse (or midwife) program. If you have any questions, please ask and I will try to answer.

MG