All good advice, I have only one tip to add that I haven’t seen posted anywhere: in my fortress, I have something similar in that the flux stone is 20z layers down (took quite a while to find it, was getting worried). Rather than build all forges 20 levels down, I use haulers to bring the rocks up. BE CAREFUL – as Toady One pointed out in one of the DFTalks, hauling jobs stack up and take precedence over everything else so, it’s quite possible to have your dorfs starve to death because nobody is moving food because there are so many other hauling jobs stacked up. For my initial forges, a 5x5 stone pile of marble was more than sufficient – and still is, years later. Here’s the trick: I didn’t make a 5x5 marble-only stone pile. I made 5 adjacent, 1x5 marble-only stone piles. Each one has three wheelbarrows by default (this assumes the fortress has 15 wheelbarrows). Wheelbarrows navigate stairs so as long as you make stairways 2 wide, no bottlenecks. As soon as the stockpile is filled, it takes only a couple of dwarves hauling part time to keep it continually stocked. That “5x5” marble pit is the only stone pile in my fortress; every other level has garbage (stone) dumps next to masonry and mechanics workshops but they’re nowhere near the marble so, it works out OK. Minecarts are a way cool idea but a pain to manage and really, wheelbarrows are more than good enough for almost every situation and certainly for stone or ore. In a mature fortress, there are enough plebes around that it doesn’t matter; starting out, it’s a good idea to keep the stone haulers limited (Dwarf Therapist) or at least have one or two dedicated food haulers. THAT’S been pointed out many times over the years but I’ve never seen a post suggesting breaking a dedicated stone stockpile into adjacent, smaller piles (which isn’t to say there isn’t one or twenty, just that I haven’t seen ‘em).
This is Dwarf Fortress. There is no 'Simple Advice'.
Maybe the best advice of all.