Sounds like a cool goal. As for jackets: Most hard shells have a lot of bells and whistles and get really heavy as well as expensive. I have used a cheapy eBay cycling ran jacket for just this sort of thing. They are really minimalist with very light and pack down to nothin with only a rear pocket but totally water proof. These are not made by any recognizable brand name. But check that type of garment out. It used to be that several of the bigger brands made water proof light weight jackets and maybe someone else knows of one. But mine was under $20 rolls up to no bigger than a fist and keeps the rain off in a pinch.
As for fueling strategies: This is high individual so not general recommendations are possible. If you are highly fat adapted then you won’t need much. If not then you’ll need a lot of sugar to get you through the race. I’d concentrate on getting very fat adapted to start with. Then try different eating methods in your longer runs to find what works well for you.
Poles work well on steep ascents and descents. They will slow your descent though as they slow the arm turn over so you can haul ass down hill as easily. Try them on downhills in training and if you think they help or hurt. I think if you are well trained and have sufficient leg strength you won’t get much benefit.