Altitude sickness really varies from person to person. Some people didn't even respond when they went to Everest base camp, and some people just got altitude sickness when they arrived in Lhasa. No matter how healthy you are, I suggest you go to the drugstore a few days before you come and buy some rhodiola. Take precautions before they happen. If you really want to come, it's okay to buy some plateau or oxygen.
The locals are relatively simple and enthusiastic, of course. There are not many taboo things, just pay attention to taking pictures in temples. Many temples are not allowed to take pictures.
The consumption in Lhasa is higher than that in first-tier cities. Eating, drinking and having fun are not cheap. Because in Lhasa, many things are not local.
If you don't camp, you don't need to bring sleeping bags and tents. If you go to Everest, take a sleeping bag. You'd better take your jacket. I don't bring my survival tools. Trauma and oral medicine depend on your physical condition ~
The route you want to take can be roughly divided into two. You can take the train to Dangxiong first and go to Namco from Dangxiong. Camping in Namco feels good. There are many stars at night. Then go to Lhasa from Dangxiong and rest in Lhasa for a day or two. Then carpool to Everest. The route to Everest generally passes through Yanghu and Shigatse. In this way, when you come back from Everest, you can take Linzhi to Yarlung Zangbo River, and then take the 3 18 Sichuan-Tibet line directly. Considering not going back, Everest can take a bus from Lhasa Station to Linzhi, and from Linzhi to Yarlung Zangbo River. Or carpooling will drag you back to Lhasa.
I hope the information provided can help you ~