Listen to Tone... this looks a lot like what he must build his kits from! ;-)
You won't need a heavy-duty solenoid, as the latch mechanism is VERY light. The heavy duty solenoidss are for unlatching the side doors, which are a lot tougher.
From my experience, I would suggest you buy and install the extra door popper spring, since my setup (with the one spring Tone's kit provided) doesn't open if the VX is pointing even slightly downhill, or if it VX is parked across a slope leaning to the right, or...
I dont think this setup needs a pulley - I think that black tube-like thing at the top of the picture appears to be a "sleeve" that the solenoid cable runs through (working like the brakes on a bike). I might be wrong, though.
Tone is right about the pin switch, though... The other two reasons for installing the kit are to wire the rear hatch into the alarm system AND to get the dome light to come on when you open the hatch. Tone's kit accomplishes both of those things, this kit does neither.
Anyway, great find!!