@jmaloney as Kevin said, don’t worry about that stuff too much. Do pay attention to the wind though. Hopefully you can get a practice lap in and warm up. It’s a SW wind, so a cross tail wind on the climb but the descent will be tough with those gusts, especially the first large bend going downhill. You’ll carry more speed into it than the lower sections of the descent, so I’d advise you keep an eye on others as people will get blown toward the inside of that turn.
This is your first race in E4, so just have fun and enjoy the experience. The peloton usually stays together in that category, but Mosport is a race of attrition with all the climbing. If you have the same fitness you had last summer you can probably attack and stay away toward the last couple laps, or earlier, depending on how you feel. There could be other fit people capable of riding away from the peloton and upgrading easily, or not. You’ll figure it out over the first half of the race. At the end of the day it’s better to go for it and leave nothing in the tank than just sit in the pack and sprint for 10th.
It’ll be a cool morning, so I hope you have some warm, but not too warm kit to wear. A vest will be key if you have one. If you don’t I have a medium Faction vest you can borrow and a medium “fino therm” long sleeve cold weather WCC jersey that’s good in those temps with a light base layer under it. A good pair of wind proof gloves will also save your hands from freezing as half the lap you’re not putting out a lot of energy and will be getting blasted by the wind. Let me know if you need anything, I could drop it off tonight.