Have to disagree with the “don’t go out too hard on the first lap”. It’s cross, start as hard as you can, and then hang on for the rest of the race 
Maybe not in your very first race. Or if you’re very good and know what you’re doing. But for the rest of us, everyone else will sprint off the line, and if you don’t all that will happen is that you sit behind everybody for the rest of the race.
Have a Blast! You will be amazed at how fun and pain can exist at the same time. Whether you finish first or last there will be another race the next week. There are so many races that go on inside the race. If that is where you are then race each one of those. Learn from the people around you (good and bad).
Totally correct. If there is a pinch point on the first turn you should be gunning for one of those top 5 spots leading into it.
Carrying speed through corners is absolutely critical, so is trusting the grip in your tires. There are parts of course that can only be ridden at a certain speed despite threshold. In other words, a person with a 400w threshold will be riding it at the same speed as someone with a 300w threshold due to the design of the course. Trying to put out more power just isn’t possible or would lead to going off course, crashing, etc.
The key is being able to not bleed off too much speed by over-braking…I see so many roadies ride too gingerly through sections that could be ridden flat out.
As you move up in categories there is more emphasis put on being a better bike handler given most everyone is comparable fitness-wise.
Remember, we are talking to a new CXer, Cat 5. The most important thing is that he finish the race on a positive note, which in my book means positive splits on the laps. It doesn’t do any good to go out super hard in the first lap and then blow up and have everyone pass you in second half of the race.
Can’t believe no one has suggested getting a ridiculous looking skinsuit, theres a ton of wild looking ones on AliExpress!
This. And just try to bunny hop a barrier at least once.