I've read a quote from Toady that said that weapon quality improves effective skill levels
I've read the same on the wiki, but I thought that wisdom was outdated. Do you remember whether that quote you're referring to was about the current version? Because if yes, and if the common wisdom of sparring becoming safer with higher weapon skills is true, then a high-quality weapon would most assuredly lead to safer training. A high-quality silver weapon, mind you, not a clownite one.
Hmm... Just found the quote on the wiki again (it's on the item quality page), and now it is under a label for a specific version (23a), but I never remember seeing it there before. Odd. I had just assumed that information was current, but if it's obsolete it might not matter.
But yes, if it is still current, MW silver would be the best for sparring. Though the fact that it refers to 23a doesn't make it certainly inapplicable now... Annoying
Edit: By happenstance, I found Footkerchief quoting a place where Toady said that the quality-based skill modifications are, in fact, still applicable. Bottom of this post. So, the question is still open (not answered, as such, since damage-over-time with no-quality and MW-quality from sparring isn't clear, but rather open).
I'm building a magma-fall in front of my fortress, then raising my drawbridge to block the magma from entering my fort. One problem - no bauxite
How can I find some bauxite? Or, failing that, how can I build a pump stack and drawbridge safely without any?
Bauxite is vastly overrated. It is found in large clusters in sedimentary rock layers, which are fairly uncommonly found near magma. While it is the only magma-safe stone (mostly), most magmaworks I've built haven't needed it at all.
To make a "magma-safe" drawbridge without actually making a magma-safe drawbridge, just make sure you always and without fail raise it before magma would cover it. To make a "magma-safe" pump stack without actually making a magma-safe pump stack, just use fire-safe materials to build the pumps, use the pumps themselves for the stack's power system, and make sure that no magma ever gets into the passible intake end of any pumps. To use the pumps for the stack's power system, build floors and walls like the following:
======
=.+.+=
======except for on the lowest level, where you omit the hole between the two floor pieces. Have one level just like that, though perhaps rotated, then the next level up flipped 180 degrees. Put the passable tile on top of the first floor tile with the output leading onto the second floor tile. This makes each pump output directly into the input tile of the next, and all of the pumps will be hanging and attached directly to the ones below and above themselves such that power will transfer. Connect the power system from outside the stack from the side to one of the stack's passible tiles, with a lever-linked gear assembly somewhere along the line so you can cut the power to the stack; this will allow you to do without a door or somesuch at the stack's top for toggling the magma-fall, which you can't do without bauxite mechanisms.
...If that's not clear enough, which it might not be since I know what I'm talking about and I'm still confusing myself, ask someone else