Hi Maarten,
I have a fair bit of experience shooting video with the Canon 5DII and 7D – in fact our upcoming tarpon movie was shot almost exclusively with these two cameras.
– We used follow focus rigs from Half Inch Rails – very affordable compared to many other options. I put a short review here:
http://www.cinema5d.com/viewtopic.php?f=33&t=15517
– I also recommend the LCDVF (viewfinder). It works a treat and is much cheaper than the Zacuto.
– Get yourself some variable ND filters, they are indispensable for DSLR video.
– cinema5d.com has a wealth of information. Understanding the basics (180 degree shutter rule, etc.) is important for good results.
– The Røde Videomic is a great, affordable microphone.
Let me know if there’s anything else I can help with.
Jan 🙂