Not sure if it's a bug or intentional but you can "Find" equip you want and run the stage even if you haven't unlocked it yet. Just ran Stage 55 hard despite still being on the 30's.
Also pulled Micah from my free pulls, was rather surprised. Gonna pump her with attack speed and see how fast she can shoot lol.
And that Lv7 to 8 storage building... 3 days. I'm thinking you're better off saving for the item that lets you build multiple since it's permanent that spending it on 500 pulls, at least til you've bought it. With the time it takes to upgrade buildings and the only way to hasten is with gems/cash, you'll eventually reach the point where you can't spend money on anything and just be wasting it. At least with Mononofu, as mention above, you could do so from the start and the game also gives you many items to reduce construction time.