The medical's not *horribly* onerous unless you have some kind of pre-existing condition. Even then, quite a lot of conditions can potentially be approved but it may take quite a while and a lot of extra appointments. It's hearing, sight, blood tests (cholesterol, diabetes etc), ECG, mental health, blood pressure, height, weight, reactions etc etc - it's very broad ranging. According to my doctor, they're pretty much looking for any risk factors as well as any condition you might currently have. If you do have a medical condition of any kind, they're also looking at how it's managed. They're very conservative.
It can also take quite a while. The actual medical is about 2 hours, but it's CASA that approves it after their medical officers have reviewed the DAME's report. If there's anything even slightly out of the ordinary, it *will* be queried. eg. I had to provide detailed surgical reports from 20+ years ago (which really wasn't easy!).
Until you get that medical back from CASA, don't assume that you'll get it. I wouldn't do anything you can't reverse until you have a definite start date (which may be many, many months away). You won't get that until the medical's approved.
Cheers,