I have worked part-time for about 11 months.
1 The training time is 2 months with pay, mainly in stores, and a small number of courses are in the company. After 2 months, I have an assessment, but it is difficult to pass the night shift.
2 I am responsible for closing, and the closing time of each store is different. Generally, I can leave within half an hour to 1 hours after closing.
3 I really have to carry a lot of things, such as drinks and food. However, it is not difficult to remember because of its strong practicality. It is not too hard to work in a store with a small passenger flow, and it will be more interesting than a store with a large passenger flow.
4 English requirements are not high. You can communicate with guests basically and understand their orders. Of course, if you have higher requirements for yourself, you can take the opportunity to practice your oral English.
Personally, though the salary of Starbucks is very low, it is more interesting than McDonald's and KFC, and you can learn a lot (and lose weight by the way). Of course, you must have enough spare time. Good luck!