You should be able to get dexterity bonuses on equipment, if you aren't going to be using any skills that require a dagger equipped.
Yes. You can also craft poison potions or food (though poisoned food removes any other bonuses/penalties the base food may have had).
Yes. Mid to late game spells may be able to do higher DPS or add CC, etc, so some people end up just using wands for the bonuses. There are people that think dual wands are OP and some that think they are useless. If you can find a belt with +1 Dual Wielding, that would save some ability points.
The Teller of Secrets should only have one copy of the books; they don't restock.
Crafting can be very helpful, but isn't necessary. See what you can get from gear, the Pragmatic trait bonus, if you have a spare talent point for Scientist and if you start running into things you'd like to craft but can't.
The talent point for a single ability point in the EE is a bad deal, unless you are desperate to open up a new ability category, or only need one more point to get the next level of something, or there really aren't any more talents that you want.
