Sony claims that the camera can work at 8 or 9 feet out but when I sit on my couch that far away I get the same drift issue. I put a chair in front of the couch, in the 5 to 6 foot 'sweet spot' of distance from the camera, and the view drift was almost entirely eliminated. It's still off by a few degrees, maybe less than ten, so they still have some work to do.
I would recommend making sure you're seated between 5 and 6 feet away, lights are dimmed if possible, and fully power off your PS4 (maybe even pull the cord afterward for a few seconds) and restart it before trying the headset again.
If you notice any "jumping" where the tracking on a controller seems to warp across the screen instead of just wobbling in place, make sure to power down for that as well. There seems to be a tendency to have some background stuff going on in the PS4 that affects the camera operation and sometimes makes the feed stutter.
Still, if you have the time don't hesitate to call Sony (call them, don't use the web chat) and troubleshoot it with them. They need to know it's a prevalent issue so that they will work on a fix. They're open until 10 PM Pacific so you should be able to get help even in the evenings, you're not limited to U.S. business hours.
Their phone number is 1-800-345-7669 and the link to their troubleshooting guide for PSVR is https://support.us.playstation.com/articles/en_US/Decision_Tree/PS-VR-Help
Best Answer
Yes you can use a EU Playstation 4 and a US Playstation VR. However do make sure that you have an adapter for the difference in the US and EU power cables.
A few sources:
https://www.reddit.com/r/PSVR/comments/4vsvao/will_there_be_a_region_code_for_the_psvr/
https://www.quora.com/Can-I-use-PlayStation-VR-Launch-Bundle-in-other-countries