Shaping teens' decision-making regarding sexual activity?

LOL this is a massive set of questions and I'm sure there are many books/scholarly articles for advice on the subject. But since you are soliciting some general responses:

1. Yes, I do care about the 'when' my teens are involved in sexual activity, many studies show that the later it happens the better for their physical and psychological well being.
2. Yes, for the reasons stated in answer 1.
3. IMHO waiting until at least senior year of high school is of benefit.
4. Yes, because conversations from birth onward have helped to shape my teen's decision making, as with all other areas of their life.
5. see 4
6. Teens will 'do what they will do' based on these same lifelong conversations.

Every kid is different and every family is different in the way they talk about, consider and model healthy sexuality. It worries me a bit when you say " I think my daughter has basic information about sex." These conversations have to happen all along, not at once, and with increasing degrees of specificity. It's great that your daughter is asking you these questions, are you sure when she says 'sleepover' that you know what she means by this? I would have taken the opportunity to have a conversation about what age SHE thinks it is appropriate, what that might entail and why she feels the way she does. Part of the key to navigating these conversations is asking questions as well as giving our opinions. But the asking is always great - that they feel free to ask you questions and care about what you have to say. These are prime opportunities for great dialogue.

As a last thought, we are a household that practices a faith, and that is a large part of the way we think about, talk about and consider all sorts of issues in our home. This has been important in shaping our children's views about sex and sexuality, as it is in many families.  I hear these kinds of questions far more among my friends who do not consider themselves affiliated with any particular spiritual tradition, just an observation.

You are asking such great questions! And it’s such a good sign that your daughter came to you with her question!

Here are my thoughts (as a mother of a 20 yr old and a 7yr old)

— I’m curious why your daughter chose that moment in time to bring this up: is she hoping/planning to be sexually active soon? Has she already? Is she worried about privacy? Is she asking for your advice or your permission or about a family rule? What are her values around this question? 
— my response about sexual activity in my home would be child and partner specific, not based on age. Do you know her current partner? Have they spent time with your family? Do they seem capable of emotional and physical responsibility — for their own and your daughter’s well-being?

— I’ve thought a lot about why we ask kids to wait before they are sexually active (more than kissing/“making out”) and here is what I’ve hit upon, for me: having safe and fun sex with another person requires that we know what feels good (& bad) for us, and how to communicate this to others.  It means being able to ask others what feels good for them, and to pay attention to both our pleasure and the other person’s pleasure.. This is something most grown-ups have trouble with! It’s a learning process, I love the book by Cory Silverberg “You Know, Sex” which covers a lot of these complexities  

— My response would also have to acknowledge that I can’t prevent her from having sex, but I can unintentionally end up forcing her to be secretive if I’m not showing curiosity and compassion. 
Good luck to you and your daughter!

1. I care
2. So many reasons to delay. It’s risky for the heart as well as the body.
3. Not an age. A list of conditions. In a relationship for at least 6 months. Has had dinner with the parents. They are supportive of each other.
4. You can’t control a teenager. But you can state your expectations. If you have a good relationship, they will want your blessing. 
    

I applaud you for your thoughtful examination of this issue!

1. I have and treasure a relationship where I feel like my teen has communicated about their readiness to explore this realm along the way, and they never seemed interested before what I deem a pretty appropriate age (now 16) to make such a decision without my direct oversight. In other words, if she said she was ready now, I would trust that; before 16 it would have been a much deeper level of inquiry for me, but even then I trusted her judgment. At 15 I put her on birth control, and knew she was completely empowered with the information about protecting herself from STD's, abuse, and everything else; she wasn't active yet, but I knew it was ahead, and when periods were painful and BC was recommended, I was happy it would also supplement a safe passage through the early years of sexual learning, when we all know that young brain decision making isn't always top notch.
2. Yes, to some degree, but I also think tremendous harm comes from telling them what they should feel about it, and denying them their perfectly healthy and normal interest as it develops appropriately. I don't think I get to decide to just tell a kid they don't get to think about it until a certain age.
3. At 15 close to 16, I was definitely already fine with my child deciding to explore intimate contact in a safe environment, although we had direct and frank conversations about respect for our household and privay during visits so we could come to agreement about what works in our home. My reading of the data has me believing that educated kids make the best decisions around things of a sexual nature, and that sex education is part of the reason kids are delaying sex overall, because they wisely understand as mine has been raised to know that sex comes with intimate consequences, beyond just STD's and pregnancy. 
4. I don't expect to be able to make that decision for a child who is now 16 if she wishes to proceed with intercourse. Source: my parents thought they could with me. Ha.
5. I don't, but I do expect transparency and my child knows this. I don't want details, but we've agreed that I am to continue to be informed if a sexual relationship is emerging.
6. Yes. I 100% think they will do what they will do, and all parents can do is keep a strong connection and provide information and acceptance. My own origin family treated sexual interest as illicit and just told me I had to wait with no reason (beyond pregnancy) given as to why. Nice girls just didn't do that, boys who talked to me only wanted one thing, etc., etc. This did not have the effect they desired. in any way, but it sure kept me from asking them for support and help when I had questions or confusion, or felt like I was ready with my boyfriend, and believed what he had to say about how we'd avoid pregnancy. You can guess how that story ended.

I've raised three teens. My two oldest were not sexually active by their own choice until age 17-18. The youngest began to be interested around 16, but didn't actually have sex until almost 18. So I was never in your shoes, but I do have some thoughts!

First I want to agree with another poster that 'Sleepover' doesn't necessarily mean sex is involved, so be sure you and your daughter are on the same page on that. My youngest, in high school, had sleepovers with a small group of friends, both boys and girls. None of them were partnered up - it was basically an overnight camp-out in the living room.  On the other hand, around the same time, my son was invited to a 'sleepover' at a friend's house that I thought, and he thought, and the girl's mother thought, was a platonic sleepover, but it wasn't. Sometimes even the kids don't know what 'sleepover' means. All three of my kids have insisted to me that sleeping in the same bed with a potential or actual romantic partner can be innocent snuggling, no sex involved. This I have never believed, but they did truly believe it themselves. So it's good if everyone talks beforehand about their expectations. 

I personally feel that 14 is too young to be sexually active. Kids at that age typically have a very unrealistic vision of what it means to have a romantic relationship. Maybe it's the imagery in music videos or the casual porn that's so accessible or the nude body parts constantly making the rounds on their phones, but whatever the reason, most young teens I have known do not have the maturity to separate the hype from the real thing. And I do remember what it's like to be overcome with passion at the age of 14.  That passion is real!  But it's not the same as getting to know another human, spending time with them, discovering their foibles, and wanting to connect in a deeper way. I can imagine that there might be 14 year olds out there who have that level of maturity, but I haven't met them yet!