Any advice for a share house newbie?

[Bagatelle]

I'm going to be moving into a share house at the end of the year and am trying to gather as much info as I can about what to expect.

I'd love to know your experiences, opinions and advice. Especially about the unexpected things - unanticipated costs, dramas, personality clashes, couple issues and so on.

Here's a little info about my situation:

I'll be moving into a four bedroom house with my best friend, her boyfriend, and one other guy. We all get along well, though my best friend and her boyfriend have a penchant for melodrama.
We're all currently studying at university (2nd and 3rd year), though there is potentially another couple moving in who are not. The situation surrounding this other couple is a little tricky. They are friends but have more difficult personalities and don't do much other that work at a grocery store and party. As the rest of us are students, we're not too keen on turning it into a party house.
The rent will be about $400 a week for the house, so it will vary per person depending on how many people move in.

Thanks!