I need some help designing an underground magma workshop district. I have tried before, with poor !!results!!. Long story short, I confused down and up, among other things.
Here's a picture of my current design.

That blue dot is where the screw pump is going to be. I'm almost certain that I shouldn't be channeling directly into the magma pipe. Should I mine 1z level down instead? How do I get my miner down? How do I get her back up? Does magma move diagonally at the same speed as orthogonally? Where should I put grates and floodgates, can I make them out of normal stone or glass? Should I? Is there any danger to walking over a magma channel on a grate? if a magma workshop is over a magma tile but the magma tile is covered by a grate will the workshop function? Do I have to worry about magma critters?
Really any advice about magma workshopping would be great.
About my design: This is a modified version of my design for the rest of my fortress. There's 4 8*8 rooms in each section, each section is separated by 3 wide hallways. Each room has 4 doors on each side(48 per section), which keeps my mason employed. In the magma design, each room has channels around the outside along with channels to pass magma to each other.