Current list: https://cubecobra.com/cube/list/fmj540

As a pandemic project, I'm putting together a cube, but I'm relatively new to cube building and looking for any advice or suggestions. My goal is a powerful, Legacy style cube with no cards from the reserved list, e.g., ABU duals, Gaea's Cradle, Recurring Nightmare, etc. I don't want to proxy anything, and I've played Modern and EDH for a while, so I have a decent collection of staples from those formats. But mainly, as a concept, the reserved list can huff my shorts.

Broadly, I want to support powerful, eternal-style combos and effects while also having enough disruption to keep that from being the only path available. I also want to have enough variety in what each color is doing that it doesn't feel like every deck of a given two-color combination plays the same. Lastly, the people I'll be playing with have specifically suggested/requested the following things, so they're staying in regardless of how imbalanced they may be: Conspiracies, Booster Tutor, draft-mechanics cards, Smokestacks, Nicol Bolas Dragon-God, 15 mana Emrakul (and some ways to get her into play). If we try them and hate them, I can change it then.

Things I especially want some insight on:

1. What do you do with white in higher powered environments? I feel like everything is either an obvious WW card, an obvious control card, or an Oblivion Ring effect. Is that all there is to the color?
2. Is it feasible to support a 5c Golos sort of deck without painless duals? I want it to be available without making 4-5c goodstuff too easy/powerful.
3. I feel like I've got a lot of mana dorks, but any deck that wants them wants like three, so I dunno.
4. At some point, I might want to try adding a storm deck, but it seems hard without things like Yawgmoth's Will and Time Spiral. Has anyone tried something like that?
5. Is there anything else I'm overlooking, or anything that seems egregiously out of line?