Wet-niche underwater luminaire flexible cord

Is it 2008 NEC code-compliant to run a wet-niche luminaire 30 foot flexible cord from forming shell continuous, without splice, underground in IMC stubbing up into a nearby garage into a metallic junction box or pulling elbow, which is connected to panelboard in IMC?

Must this junction box be listed as a swimming pool junction box (Sec. 680.24 (A)?

Originally, the junction deck box was flush and within 18 inches of the inside walls of the pool (installed in 1965). The perimeter concrete deck was removed to expose a broken gas line supplying the pool water heater. In the process, the deck box with brass piping from the underwater luminarie and with home-run metal piping were exposed.

It is intended to cut the brass pipe below ground and connect IMC to it and run it back to the garage pull box then to the panel.

What kind of connector or method is used to connect brass pipe to IMC pipe?