1, mainly shooting jewelry. Personally, if it is not very professional, D70 18-70MM is enough, because there is no need to shoot with telephoto, and this lens can meet the needs of general close-up and exterior shooting. Of course, if you use D80 sets, 18- 135MM will do. The main difference between the two is that D70 sets are better than D80 sets in terms of workmanship and materials, and the former has one more e D lens than the latter. This is why many people are willing to take D70 condoms to D80 now. Of course, I actually think it's best to adjust the focal length if shooting close-ups. It is recommended that you use Nicol 50/ 1.4 or Nicol 50/ 1.8. Many professional photographers use it, and the price is not high. As for which one to choose, it's up to you.
2. The 2.D80' s built-in flash is very powerful. In fact, it also comes with strobes, which is quite useful for shooting jewelry. The related functions are introduced in the manual. There is no need to buy an external flash in the early stage. Of course, if I buy it, I will recommend buying Nikon's SB600 and SB800. These are two quite good flashlights. The price of 600 is around 1600, and the price of 800 is around 2500, all of which meet the requirements of professional shooting.
3, tripod price span is very large, generally speaking, from tens to thousands, personally think that according to the current situation, it is possible to match an ordinary domestic aluminum tripod. Of course, it is best to have a tripod that can be quickly disassembled. The key is that the workmanship at the node must be firm, and this tripod is now around 300.
As for your budget, there is no need to match anything now, because this is enough for you to play for a while at present. If you are crazy about large aperture, I think your last movie Longteng 17-50/F2.8 is also a good choice. The price is in the early 3000 s, the cost performance is super high, and the imaging is better than the two I mentioned above. If you consider having a telephoto lens, you can also buy a 70-300/F4.5-5.6 VR. This head has good cost performance and good imaging, and the price is around 3700.
Of course, if you want to shoot macro, I think Nikon 60/f2.8 macro and Longteng AF SP 90/F2.8 macro are suitable for you. Both of them have sharp imaging and good macro effect. The price is also around 3000, which can be considered. But I don't think it's necessary to shoot jewelry at a macro. Relatively speaking, it is more valuable to use a better flash.
5, d80 is a good machine and worth buying, so I don't recommend anything else.