They're not really a pairing I ship, but I can have a go (based on the new film, I've never seen any of the original series)
1. What they most commonly do during sex: I think Kirk talks a lot, mostly to make Spock come up with ever more creative ways to shut him up
2. Who has prettier hair: Kirk, definitely. Spock's lovely, but his hair is terrible
3. What they argue about most often: Who should be the one risking his life in stupid but ultimately successful endeavours to save the world
4. Who'd cope best if the other one died: Probably Kirk, at least if it happened not too long after Vulcan was destroyed, because I could see Spock just falling apart because this was the straw that broke the camel's back. On the other hand, Kirk would probably drink and fight his way through grieving, which isn't all that healthy as a coping mechanism
5. The happiest plausible happily-ever-after I can think of for them: I think they'd both be happiest continuing to explore the galaxy in the Enterprise for the rest of their days, until they die peacefully in bed together
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1. What they most commonly do during sex: I think Kirk talks a lot, mostly to make Spock come up with ever more creative ways to shut him up
2. Who has prettier hair: Kirk, definitely. Spock's lovely, but his hair is terrible
3. What they argue about most often: Who should be the one risking his life in stupid but ultimately successful endeavours to save the world
4. Who'd cope best if the other one died: Probably Kirk, at least if it happened not too long after Vulcan was destroyed, because I could see Spock just falling apart because this was the straw that broke the camel's back. On the other hand, Kirk would probably drink and fight his way through grieving, which isn't all that healthy as a coping mechanism
5. The happiest plausible happily-ever-after I can think of for them: I think they'd both be happiest continuing to explore the galaxy in the Enterprise for the rest of their days, until they die peacefully in bed together