Good questions.
1) What would I change? The attendance policy, it really sucks (I can go into more detail if you'd like). Some of the teachers aren't great, but then on the other hand there are some pretty fantastic lecturers, the "breaks" we have... after first year there is a 3 week summer "vacation" while most schools get a few months. The fourth semester is long (november - april) and ****ty with lots of tests and unnecessary classes w/ tons of overlap - I would want to change the curriculum to remove some of those classes, and lastly, the policies with tests and repeat questions/challenging questions/etc is pretty stupid. Don't get me wrong, the school isn't perfect, but I am pretty sure every school (pod, md, do, masters, etc) has its fair share of bull**** that people have to deal with, so you gotta remember that too.
2) Get good at time management lol. The classes arent per se difficult, but there is a **** ton of info needed to study for the majority of tests, so you gotta put your axe to the grind stone more often than not - so, learn how to budget your time so you can enjoy your hobbies. But coming from undergrad the classes here aren't too much more "difficult", it is just a lot more info you need to squeeze in a shorter amount of time.