Re: credit transfer, that may occur at La Trobe (unsure), but it doesn't occur at Monash. The reason for this is at Monash you study one 24 point unit per semester (rather than four 6 point units), and as the physio units are only offered in the physio degree, it's impossible to do some of the units in a different degree and get a credit transfer.
You won't get exemptions from topics or anything but I guess it'll make it easier for you if you've studied similar content beforehand. But yeah, everyone does everything together in the Monash physio course
I believe some people in my course already have qualifications in exercise science/physiology and they're still taking the same path as the rest of us. Plus, it's not like you know it all after you've done one unit on a particular thing, so even if you've covered similar content before, there's always more learning to be done.
Hope this made sense, please say so if it didn't
Will answer the OT vs physio question later, but in a nutshell, they're pretty different professions that often work together, and obviously everyone is going to have different thoughts about OT and physio. Personally I don't think I could be an OT but that's just because I was never drawn to it - personal preference.
I'd recommend checking out the Australian OT Association website (not sure of it's official name) and the APA (Australian Physiotherapy Association) website to check out more about both professions.