no there is no advantage tranferring within the univeristy.
its all handled externally by uac and higher prefernces would go to those with the highest GPA, not which uni you attended... which would be too subjective.
and yes u would need to still do stat to enter pharmacy at usyd, no matter which year u want to enter
yes u can transfer after 1 year of adv sci, but you would not of done the required 1st year pharmacy subject which means you would still need 4 years to complete the pharm course even after u did advance science