1. I think you still need to pick an Element. I could be wrong, of course.
2. Yes, that's exactly it. Check out the Evocation section on Blocks on p. 252.
3. Yes, that's allowed. Actually, look at a Warden's Sword, it's countering and killing spells are active effects usable whenever you like. Bear in mind the need for a to-hit roll.
4. Doesn't look like it, mechanically. I'd personally say you don't need Crafting to maintain/own Enchanted Items, but do to make them, though you can presumably replace them between scenarios.