[Aussie Mike]

That little piece on the fuel rails in your pic is actually a damper. It's a spring loaded reservoir that takes some of the surge out of the fuel system as demands increase and decrease. Because the regulator is right back in the tank on the stock setup it's sometimes not as responsive as a regulator right up near the rails. The damper fills in the holes.

The carbon canister purge valve is actually a black plastic solenoid valve about 1.5" in diameter and about 3" long that's cliped to the manifold just below the fuel rails. There's a couple of wires running to it and it's locked off when the engine is not running. Once it fires up it will let the engine vaccum suck the fuel vapours out of the carbon canister.

There are plenty of options open for pressure reg setups. You can run the factory in tank pump setup cut down and installed in the top of your tank. You could also use an after market reg back at the tank and plumb it in the same configuration as the factory setup. This is probably the easiest way as you will only need one fuel line up to the motor.

Alternatively you can run a feed line and a return line up to the engine bay and install the reg in the engine bay. This could be connected via a single line from the reg to the factory rails. Most after market regs have 2 ports on the high pressure side. One is usually used for a guage but it could be used to connect to the rails instead. I've gone one step further and used after market rails and have cool fuel constantly circulating through them with an inlet and an outlet on the rails.

I've got some schematics for different fuel systems I drew up a while back. I'll see if I can find them and post them up.

Cheers