1)
Why is it written ha'Sheloshi, and we pronounce it ha'Sheloshah?
1.
Radak: The writing is [ha'Shalishi] like "v'Shalishim Al Kulo" (Shemos 14:7 - captains). We pronounce it Sheloshah, for he was the head of the three who brought the water, and an officer over them.
2)
What is the meaning of "v'Lo Shem ba'Sheloshah"?
1.
Radak: He was mentioned for Gevurah with them. Malbim - this is because he waved his hand over 300 corpses, like Adino ha'Atzni.
