The owner of Imgflip is in charge. You've probably seen it, but there a couple ways to contact Imgflip here:
imgflip.com/about Suggestions about how to make Imgflip better are always welcome.
I'll help where I can, but I don't have answers for every question. I don't think popular templates or user contributed templates have any kind of pre determined stream restriction or designation, other than that some are already NSFW.
I'm drawing on my own experience here, I've had plenty of submissions never feature or get disapproved. Having that happen can take some of the fun out of imgflipping, I can relate to that.