There are some complications I see with trying to do this. The first is that the text editor for entering comments is drawn into the page, and doesn't offer any Html structure that would allow for hiding the icons that offer the options of adding photos and images. So users will still see those icons and try to add photos and videos anyways.
The second problem is that once they do upload a photo, or add a video, there will then be a comment that is likely blank, or missing content that would have made the post make sense in many cases. That would not only be confusing to people posting when they don't see what they were allowed to enter, but as well, it would be visually unappealing to people looking at the post wondering why there is no video or picture like they expected, and at times wondering why the text said there would be a video and picture but then there is not.
The last need is a somewhat complex process that I've never personally attempted, so I don't know if there would be any complications. It would require a good bit of Javascript/Jquery work to hide all comments except for 5, 8, or 10, and group them all into pages. The easier, yet still difficult approach would be to show 5, 8, or 10 at a time, and then have a "load more" button below them that would then load 5, 8, or 10 more. It's not something that anyone is likely to give you the code for based on how lengthy of a process the research and coding would take. You would have to know how to do such a thing yourself.
At a quick glance, this is how you would "hide" the pictures and videos from the comment box, but again, it comes with complications that "myself", I wouldn't be happy with:
<style>
.SUI-CommentText img, .SUI-CommentText iframe{
display: none;
}
</style>
