Hi!
Congratulations on the vacation scheme!! I have made a few previous posts on the feedback that I received post-VS that might help you give an idea of what firms are looking for, so I have quoted them below.
In terms of coffee chats, I would agree with what others have mentioned and would definitely suggest using them as an opportunity to learn more about the firm and its work, rather than treating them as a tick-box exercise. I found that my schemes went better when I was more selective about who I arranged coffee chats with, rather than trying to speak to as many people as possible.
I would also encourage you to reach out to people at all levels of the firm, not just senior associates and partners. Some of the most insightful conversations I had on vacation schemes were with solicitor apprentices, so it is definitely worth speaking to a wide range of people.
In terms of how many, it really depends on your schedule and the length of the scheme, but I would generally only plan a handful per week. Otherwise, you might find yourself rushing around and not having enough time to focus on the work you have been given.
I also found it quite difficult to come up with questions beforehand, but it often works better to go in with a few prompts and let the conversation flow naturally. In my experience, lawyers (usually!) enjoy talking about their work and career path, so if you show genuine curiosity about what they do, the conversation tends to develop quite easily.
Best of luck with the scheme, I'm sure you'll smash it!!