I'm only a P1, so take what I write with a grain of salt.....
Cumulative GPA must be 3.0+, but I remember the assistant dean mentioning a 2.8+ for the first semester or yr. Best not to place yourself in that position-so kill the first set of exams (this year we had/are having a mid-term and finals week of 4 and 5 exams back-to-back respectively). If you perform poorly on an exam, seek out the course coordinators, tutoring with friends/Rho Chi, etc. Do not wait until the last minute before asking for help. Stay on top of things, and you may find the classes less difficult than undergrad. Most lectures are recorded, powerpoints are online, and some classes have clicker quizzes that count as extra-credit (e.g. Pharmacy Practice, Biosystems (Physiology)). According to upperclassmen, those points make a huge difference (approx. half a letter grade for full marks). The lowest quiz score is dropped too. Not a bad deal at all.
As far as the end of 3rd yr exam, I heard that you get 1 chance to retake, but I do not know what happens if you fail again. My information is limited, but there is another board member who might want to further elaborate, and who has actually taken the test.
If you fail a class, then you are held back 1 yr, where you get the pleasure of retaking it again. Do not take the classes lightly, overconfidence can = failure. Failing a class by 1% is very tough medicine to swallow.