1, EAST is a relatively large UPS company, and it is normal for new people to have a large flow. Because I didn't find my own position. According to what you said, a lot of people were recruited, so most of them must have left by themselves, because if there are large-scale layoffs, the company's reputation will be damaged. It can be seen from here that they will definitely let you start from the grassroots level, which is more difficult.
22400 is really a little small for R&D personnel (technicians). But for newcomers, it is still possible. Maybe after the past, what you started to do was not research and development, but learning, and then repairing (getting familiar with the product). After all, you switched to research and development. When you say you can get a raise, it is usually after you formally enter the R&D department. Generally, large companies will not let new people do research and development in the first place. After all, I don't know anything about products.
There are opportunities, depending on the importance of your work and your position. If we go step by step, it will take a long time to adjust wages, at least one year.
4. Generally speaking, it is technical, and I will probably stay in the post before or after sales for a long time, that is, debugging or repairing the machine (because I also work for UPS, the East UPS is not so good, but repair rate is a bit high).
It's all my own opinion. I also work at UPS. I went to the factory to read some information. Although you can't guarantee that you will be all right, you are half sure.