A few comments:
1. I love this guide. In all honesty, right now if Toady were to just adapt this into a play-along tutorial in DF he could strike that off the list of things to do, it teaches you all the basics.
2. You mentioned you were going to do a pumping/mechanics tutorial next. Make sure you cover the ins and outs of pumping magma, I still can't get that to work right. You also might want to mention trapping the magma channels for players who don't want to use the fortification exploit or who are dealing with undead imps (who I've seen slip through them before). Bauxite mechanisms with iron/steel weapons or iron/steel/nickel/nickel silver cage traps (one for each imp in the pipe) will keep them from ever reaching your dwarves.
3. If you're planning to cover biomes and wild animals, you may want to upload a second map (or just include it in the original download) for an evil biome. Once players are used to playing in a normal or good map, they're ready to learn the ins and outs of surviving werewolf attacks and warding off beak dogs and undead livestock.
4. You may want to cover metalcrafting and metalsmithing a little more in depth. For months I thought metalcrafting was a waste of metals until I realized that six exceptional aluminum cups can buy out a wagon, and copper bins, barrels, and cages are a great way to train up metalsmiths for designing metal furniture (I think that metal ores having the same value as the metals will probably be fixed at some point, otherwise there's no reason to smelt metals except to make weapons and armor).
5. In the advanced tutorials, if you want more material, a quick overview of installing or even creating mods would be appropriate.
Some of these things may already be in there, I stopped following the tutorials right after you got to the magma and just spot-checked em, but those were the major hurdles I had to get through when I started playing for real.