4 - Shalu Shalom Yerushalayim - regarding the forged Yeushalmi to Kodshim
5 - The Seforim of R. Moshe Leiter (search for משה לייטר or לייטער) - I don't know very much about him but the articles I've seen from him are generally very good. His Zuto Shel Yam is not dissimilar to R. Reuvein Margolies's style of Mechkar and his B'Shulei Gilyonei is also worth checking out.
6 - Chiddushei Rachah 1, 2- R' Chaim Hirschenson on Horiyos - Volume 3 contains many interesting letters.
7 - HaMisderonah (search for המסדרונה)- This is the periodical published by R' Hirschenson while still in Yerushalyim. See the end of the 3rd volume for an very interesting letter. In the same volume we have Chiddushim of Michah Yosef Berditchovsky on Kesubos in which I think one can already see some of the ideas that he will develop in his later writings.
8 -Ohel Moshe 1, 2 - R' Eliezer Moshe Horowitz of Pinsk, father-in-law of Torah Temimah (a hesped by the latter of the former is available at Seforim Online). Judging by his hagahot to Shas this should also quite interesting.