Hey there, getting into custom loops can be a bit tricky at first, so kudos to you! Each electrical header is indeed labeled, which should help with connections. If you're stuck, this video might help:
https://youtu.be/Se3sQ-7k2pUThe short 24-pin cables and the analog gauges sound like a nuisance. My cables aren’t the neatest, so I may also look into custom cables for aesthetics. I’m still trying to figure out the gauges with my 4090 and 13900ks. Distracted by other things in the near term.