Outgrew that shiit
If by fling relationships you mean casual sex or open relationships, then no. I'd never do it, or date anyone who has previously as it's a big red flag to not being able to be committed to one person in my view.
Many on this site will be but that is not without concequence
No idea. Haven't found a girl who'll play that kind of game with me. Probably just as well- I'm very good at getting found out!
I'm sure loads are but I haven't gathered the statistics