You're welcome. Re 1, see https://news.ycombinator.com/item?id=20020196 above. Re 2:, check out the timeclock and timedot manuals on hledger.org front page (I use the latter) and my https://hledger.org/Time-planning.html hacks in the cookbook and more https://plaintextaccounting.org/#time-logging tools and https://plaintextaccounting.org/#time-tracking tips.
1. What was the motivation to create this instead of extending ledger?
2. How to track time?