How to phrase question to developer without sounding stupid?

I am currently doing my first big project beyond a basic site/eCommerce site.

Through a series of fortunate events I friend-ed the owner of some websites I admire (that make $10M+ a year according to Business Insider. They are sort of dating websites. Social networks of sorts.) on Facebook. I messaged him, told him I was working on a project and I admired his work, and he said if I had business questions I could ask his advice.

I really want to ask him what his websites run on, whether it’s WP, or he built them himself from scratch originally, or used software like Skadate or maybe even a white label dating kinda thing. If I could I would ask how much it cost to get a certain one of his websites developed and who did it. Because I would use them. But I feel that would be too far?? We wouldn’t be direct competitors but I think his users would want to use my site. Is there a way I can see who the developer was somewhere?

How should I phrase a single question to him?? I want to ask in a way that I don’t sound like a total n00b, and keep it short and sweet. I was going to just ask what CMF his sites used but I don’t know if that’s the right term???

Help? ?? Thank you!!