Hi! I have a few thoughts that I hope may be useful.
With # 1, we haven't found a replacement for surveys/interviews, but have found value in monitoring signals that help us focus our interviews/user-journey-mapping like lead-time, ci-time, desired/undesired-pattern-usage, etc. Often this supplemental data is helpful to contextualize survey results in a given cohort. (ie: Why is lead-time lower with Typescript changes than Dart changes). Another thing we've started to do is to prompt for feedback within context. For example, we provide some CLI tooling to engineers and when they run it, we periodically ask them for feedback as part of the CLI running.
With # 2, we face a similar challenge with documentation in that we have multiple systems that house it and no real common thread or standard throughout. We're in the process of implementing a 'Golden Path' model, similar to Spotify. In this, we're consolidating and curating documentation into a single place, and cataloguing all of the steps engineers need to follow to accomplish tasks. This will be useful in two ways:
1. Engineers will have a curated documentation experience that supports the tools and processes we recommend and support
2. Product with have the equivalent of user-journey maps that will help identify which parts of the path are less-than-golden and where opportunities for improvement can be found.
Hope this helps! Who else has ideas to share?