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3. Yes, you have that K, but this is about as bad a hand as you could have for a first seat preempt at equal vulnerability. 

3. Seat and vulnerability matter. This would be a good preempt first seat at favorable vulnerability (white against red) or equal white, but we are in the most cautious position: second seat, at unfavorable vulnerability. We have much closer to a minimum bid for this position than a maximum. 

Other. 3NT is the right call here. It's possible you read a book at some point that said "3NT shows a solid suit" after a preempt. Well, in this context, this is a solid suit. You could have had a MUCH worse hand to preempt. I won't disclose some of the bids Marty Bergen perpetrated (they changed the laws of bridge to stop him), but in modern bidding, it's "normal" to preempt with KJ9743 and nothing outside in this position. 

3. We have an outside feature AND we like our hand even in second seat, so we show the feature. 

3. This is a good preempt and you should choose to show a feature. The textbooks say a feature should be a king or ace, but QJx is basically a king. Don't show shortness as partner might have ideas about 3NT that depend on your feature being an honor. 3NT would've been ok as well as long as you don't bid 3 or 3. 

3. This isn't a terrible preempt, but when you're vulnerable, partner expects something like this. We could be a king stronger for our 2 bid, but we couldn't be any weaker.