Interesting. This reminds of Egyptian and Graeco-Roman mythology (cf. the river Styx in Hades). The only ordeal I know in the OT is Numbers 5, implying drinking water...
Is shuala an equivalent to the Akkadian arallu, the domain of Nergal, more commonly held as the equivalent of Hebrew she'ol? As far as I remember, from the descent of Ishtar and Gilgamesh epic, it is a subterranean ocean one has to cross in order to reach it.
About the etymology of she'ol, there are a number of views. The most common is she'ol as the place/god asking for, i.e. claiming, the deceased? The connection to sh`l, "deep", or sh`h, desert, are more unlikely on linguistic grounds.
Another possibility (?) would be the place for the questions or inquiry of the living, connected with the traditional (later forbidden) practice of necromancy: so in Deuteronomy 18:11 "consulting the ghosts" is sh'l 'ôv. This is particularly apparent in the Samuel / Saul (Sha'ul) tradition: Samuel is asked to Yhwh, asked for by Yhwh (1 Sam 1:17,20,27f; 2:20). Israel will ask Samuel for a king, who will be Sha'ul, "asked for" (8:10; 12:13,17,19). When Sha'ul cannot ask anything from Yhwh anymore (28:6), he will ask Samuel from she'ol (28:16; 1 Chronicles 10:13). A similar pun is involved in Isaiah 7:11: "Ask (sh'l) a sign of the LORD your God; let it be deep as she'ol or high as heaven."
On your thesis, my main problem would be the lack of evidence for "judgment of the dead" in the Bible she'ol. This idea doesn't seem to appear before 1 Henoch or 4 Ezra...