'Rashi' #1: The entourage of Yabetz, who ruled over them - "va'Yhi Yabetz Nichbad me'Echav."

'Rashi' #2: Yabetz is a city in Yisachar ? "veha'Rabis v'Kishyon va'Avetz" (Yehoshua 19:20). Malbim - from Bnei Yisachar were "Yode'ei Vinah l'Itim" (below, 12:33).

Radak: Also these families were from Bnei Salma. Soferim - they were Chachamim and teachers. They dwelled in a city called Yabetz - perhaps Yabetz built it, and it was called on his name.

'Rashi': These are the names of their Batei Av. Radak - there are many Drashos about these names. A Sefer cannot contain all of them! We should not seek Drashos that are not written [in verses]. Malbim - the Drashos teach about their Chochmah.

'Rashi' #1: They dwelled in Kin (a place) ? "ha'Kin Giv'ah v'Simnah Arim Eser."

'Rashi' #2, Radak #2: They are smelters. The Targum of "va'Titnehu l'Tzoref" is l'Kin'ah.

Radak #1: This was the name of a known family.

Radak citing Sanhedrin 104a: They were from the sons of Kini, Moshe's father-in-law. They mixed with Yehudah's family, and their lineage was listed with Yehudah. Malbim - it says "u'Vnei Keini Chosen Moshe Alu me'Ir ha'Temarim Es Bnei Yehudah?", and we have a tradition that Bnei Kini went to Osni'el ben Kenaz (Yabetz) to learn Torah. They settled in the city Yabetz. Ezra taught that they were not from Yehudah.

Radak: Chamas was the head of the family Beis ha'Rechavim mentioned in Yirmeyah 35:3. Malbim - the Rechavim dwelled in tents and separated from worldly desires, like it says in Yirmeyah 35:6-10.