The Wein and SU-800 do the exact same thing in this case. You lose all functionality of the SU-800, so paying extra is useless if you never plan on moving to Nikon in the future. Both systems mentioned here are IR triggered, so distance, external light, barriers, could all affect performance. It's the reason I upgraded everything to Pocket Wizards. There was a situation with a client that I eventually worked around, but wouldn't have had if I simply spent more buying the Pocket Wizards initially.
With regard to the Pocket Wizard, the Plus X and Plus III can both trigger the camera and fire a flash, but if you want to use the functionality of a half press on the shutter, you'll need the Plus III.
Just about any triggering system should work. You'll need to be more specific as to what capability you want for the flash - full manual or retain TTL?
I personally prefer the Radio Popper branded trigger system, but there are other higher cost and lower cost options. If you just need a dumb trigger, then pretty much any triggers that just send a signal from the center flash pin should work for you,
If you need TTL, then you are looking at Pocket Wizard or Radio Popper units.