OK, here's the limited help I can offer. It all sounds very normal to me. Having your first newborn around is a HUGE culture shock. It really really really does get better.
The dropping weight - quite common in the first week or two. So long as he's feeding and nappies are being filled then he's taking food in. Give him at least 3 weeks then ask to see GP.
When you say settle, do you mean settle on his own? Some babies are really quite shocked and traumatised by the transition from womb to world. I found it helped in terms of staying calm, developing empathy etc, to try and see things from bubs perspective. You could try baby wearing - this literally means popping them in a sling so they are close to you all the time while you get on.
Cuddle cuddle cuddle, don't put him down at all, snuggle on the bed with him, let the world pass you by for a week or so while you all adapt. Lying in is sooooo important and all to often gets missed these days. We didn't do it with ds1 and deeply regret it having made a point of doing it with ds2.
Co-sleep, take it in turns to sleep, do whatever it takes at this point to get through each day.
The feeling of wanting your old life back does fade, but I think most parents look back with nostalgia, but really the amazing joy they bring you really is worth the struggles of the first few weeks.
Timelines - well most people seem to find the first 6 weeks or so the most challenging. By then both parents and bub have generally got a handle on one another and worked out routines/rituals that make day to day life easier.
Keep at it, it really is worth it. It sounds twee but they are this tiny for such a short amount of time, cherish him, keep him close and allow yourselves to bond.
This probably wasn't too coherent but hopefully thats helped at little.
(((((((((familyR)))))))))))) (thats a big hug for you all by the way )