These are some really good questions!
1) Paul may disagree with me, but obviously you can only base your understanding of the firm on what you have read/experienced at an event (if you are able to attend one), so I think it's more about tying together what you have read about STB, what you know about the wider market environment, and your knowledge of law firms in general to understand why STB positions itself the way it does.
2) I think it's helpful to understand what the market is looking like at the moment for private equity, both in respect of fundraising and entering into/exiting investments, as well as the basic drivers behind what a PE sponsor is trying to achieve.
3) People who tend to thrive at STB are those who are curious to keep learning, have an ability to see the technical side of a matter as well as the commercial aspects, and are resilient.
4) Everyone will say this, but attention to detail is important as people will not trust you can do the hard things if there are typos etc. in your work. I also think a good attitude goes a long way - no-one expects you to know everything, but a willingness to give it a go, ask sensible questions and take on feedback will get you credit.
5) The fundraising environment has definitely changed in my time at STB and we are seeing investors asking questions they might not have previously, while sponsors are looking to be more accommodating, so our approach to investor responses has had to shift accordingly. As others have said, sponsors are also looking at what other options they have such as CVs or evergreen vehicles.