Brilliant! Firstly, there's nothing there that your bike won't cope with ... it's an out and out XC route, so that's fine. It'll be a challenge in places, but that's what it's all about.
Etiquette. A lot of nonsense spouted, and a lot of ungrounded fears about trail etiquette. GO with the sole intention of riding to your pace and ability, and enjoying yourself. The only true rule is that the rider in front has priority, so if someone comes up behind you breathing down your neck you can do one of two things, which is to acknowledge them and tell them to come past as you find a piece of trail wide enough to do so.... or think "knackers to them" and carry on.
Ride circumspectly. No one cares about what you're doing, so you don't need to push yourself beyond your own limits for anyone else's sake. Have fun learning how the bike behaves on the trails.
Take it easy at first and suss out how the features built into the trail work. Stand on the pedals in the attack position and shift your weight around to change the bike's line and balance points. Weight back over the back wheel down those steps in the video, pedals level with your heels pointing downwards will mean you roll down them without going over the bars. If you feel confident enough, try giving the bars a bit of a tug to get the bike landing on both wheels not the front wheel first. Or just ride tight and keep everything smooth and on the ground....it's your choice!
Above all, enjoy yourself, and let us know how you get on.