The two on the corner are feed and return. The three near the filler are the evaporative emission control hose connections - the fuel vapour liquid separator behind the offside rear trim panel and the carbon canister in the engine bay. The Section FU manual file doesn't show the exact designations for these connections so it's best to mark them up when removing the tank. I suspect the liquid separator and carbon canister connections have internal metalwork, such as baffles, inside the tank to stop liquid fuel sloshing up the pipes to the unit but, not having had one of these tanks apart, I can't tell you exactly. Flow and return will be pretty much standard as any other closed system fuel tank.

If you feel like dissecting the old one, please remember "empty" tanks are even more dangerous than full ones for potential accidental spark ignition. Steam it out thoroughly and fill with sand or CO2 before any cutting/welding operation. A better option might be one of those cheap USB endoscope things down the filler spigot to investigate the innards.