Etiquette? If you're a decent rider on a reasonably big full sus, then it's quite easy to start in front of the DH boys and get down quickly in front of them – they spend a lot of time faffing and fannying before they actually start riding.
If you want to stop part way down, get your bike clear of the trail. When you get going again, make sure you have a good look behind to make sure you're not going to pull out in front of somebody going flat out.
Enjoy – it's a fun trail – nothing too intimidating so long as you miss the quarry gap. After the road tunnel and a short climb, keep an eye out for a "black run" singletrack on the right. Best bit of the course imo.