Make sure the Aironet IE is enabled on Mobility Express, uncheck the box under Monitor->Best Practice->Disable Aironet IE.

IW6300 is the AP recommended for C1D2 hazadous location environment. https://www.cisco.com/c/en/us/products/collateral/wireless/industrial-wireless-6300-series/datasheet-c78-742907.html

Yes, this scenario works fine, check out https://www.cisco.com/c/en/us/td/docs/solutions/Verticals/Industrial_Automation/IA_Verticals/Oil_and_Gas/ImpG/Oil_and_Gas-IG/Oil_and_Gas-IG.html

Please see Connecting Ethernet Daisy Chain section in https://www.cisco.com/c/en/us/td/docs/wireless/outdoor_industrial/iw3702/hardware/install/guide/b_iw3702_gsg.html#con_1153554, 2-pair cable is not supposed to work.