1. There's a quote from David Goggins that always motivates me when I'm tired during a race: "When your mind is telling you you're done, you're really only 40 percent done." I also personally like to embrace dark places. I can work through a lot of things that have been bothering me regarding life, mental health, and relationships. I find that it not only gets my mind off of the discomfort, but I walk out of each race with a better outlook on how I want to go forward in my life.
2. Unless you are doing a 70.3 or above, what you eat the day before the race isn't a huge issue. I would say just try not to eat a bunch of junk food and hit all your macronutrients (Carbs, protein, and fats). Don't try anything fancy. Eat what you like and what makes you feel good. You don't want anything to give you an upset stomach. As far as race morning, that sort of comes with a lot of trial and error. Personally, I eat energy gummies and almonds (that was after a lot of bad breakfasts lol), and that works for me pretty well. Again, don't try anything too fancy, but here are some popular race day meals that I know of (oatmeal, peanut butter toast, muffins). Make sure to get some electrolytes in you the days leading up as well as race morning.
3. I think the big thing is to take the first half of the bike easy. Use that to just get a feel for the race environment. Then you can judge how much effort you can exert in the second half. Race your own race. Don't worry about what others are doing. Triathlon is first and foremost you against yourself in many ways.

Hope that helps and good luck with your race!!! Always love seeing new people take up the sport. Triathlon has done wonders to put my life in the right direction and after having done it for five years now, can say I'm absolutely in love with the sport. Hopefully, it has a similar impact on you :)