Why would you change BioMed to 1st preference, just leave it in 2nd, if you don't get Monash, you'll get BioMed.
Change of preference is for people who don't know what they want to do. Just leave it as is and you'd be fine.
Hypothetically, yes, you could possibly get an interview, but why would you want to do that?
pi said Eng/BioMed at
Monash (the better uni) as opposed to Melbourne (the crappier one)

In terms of not getting into Med or BioMed, why not Science at UoM, your chances of getting in from BSc is the same as from BBioMed, don't get carried away with marketing.
In regards to Monash being blunt, well, I can't help but admit, they do have a point. If you put your holiday ahead of your interview, well...it shows which you're committed to

(Btw, @pi, Luken recieved that blunt statement

)
Moderator action: removed real name, sorry for the inconvenience