Some links for Aseres B'Teves:
Rabbi Berel Wein in The 10th of Tevet discusses why The Tenth of Tevet is viewed as such a severe and important fast day that it is observed even if it falls on a Friday.
Rabbi Yehuda Prero in The Tenth of Teves - The Power of Prayer and the Destruction asks why Yoshiyyahu sent messengers to the Prophetess Chulda instead of to Yirmiyahu. He answers with an insight from Rabbi Henoch Leibowitz shlit"a.
