1. 100 bolts is a little low - what I'd use for two marksdwarves, or what is the default reserved bolts for hunters.
Beyond that, I dunno. If you equip axe and crossbow in wrong order, then I think you might get something like that, but that would happen for both of them.
2. Well, mind the difference between regular adding to burrow and civilian alert.
Beyond that, I find most cancellations are 'caused by stockpiles in the burrow requesting stuff outside the burrow. (o)rders - (F)orbid is useful to deal with that.
3. Don't need a tower or specialized squad to deal with few birds (though that doesn't mean they're pointless things to have). On embark, butcher an animal for leather, and make 25 bolts, quiver, crossbow, set hunter bolts to 0 and tell 1 dwarf to wear uniform of crossbow, over clothes. Though note that obviously 1 untrained dude who was previously picking herbs will not be able to kill pack of 15 keas with just 25 bolts.
4. Best way to get iron ore (large
~ Magnetite and veins of
£ Limonite and
£ Hematite) is embarking on
sedimentary layers. Dig down to first stone layer in a biome, and check if you get one of those layers - if not, try again in another biome on your embark.
There's also hematite veins in
igneous extrusive, which should be present for everywhere fairly often.
Though you might have embarked on wholly metamorphic and igneous intrusive areas in same biome five times in a row, which would never have any iron ore.