Here are some developers from YT which can help you and answer some technical questions. Also YT is a huge and old project. I believe you can find a lot of people which are ex-Yandex who worked with YT.

I doubt about "a lot". Also, "already solve" does not mean "solve better" or even "good enough".

It would be very interesting to see some in-depth comparisons with already-existing open source technology (like Hadoop, Hive, Iceberg, ZooKeeper) to get a sense of when and where YT could be more effective.

I am obviously biased, but, yes, technically it is very, very interesting. Distributed transactions, kiparis, YQL are interesting. Another aspect, the only other open alternative is Hadoop, hbase and hive. They don't compete with yt on usability and developer experience aspects. Yt is much more polished, despite historical quirks.