I want to use this mod for my game as I believe it will make the endgame at least "slightly" more interesting. My 2 friends have never launched a rocket but in my opinion the process is bland and beyond easy. Does this mod improve the "epicness" of the endgame?

Then this mod is for you =)
It will requires more time, materials and a good logistics to deliver it all to the construction site.

One of my friends is "hardcore" about being true to the game developers, is there an easy way to convince him that this mod is fairly lightweight and non intrusive? My opinion is that the endgame of factorio just kind of happened to me out of nowhere, felt like Game of thrones. It seems like it should be something that requires a little bit more work; He has been fairly against adding mods from the get go.

Yeah, i understand you. I've played a lot of vanilla until it gets too easy. So I started making mods. Most of my mods will make your game more difficult. But I consider this one lightweight. Its just a bit more work to do. No big deal.