Correct. The manifold is the only piece of equipment in the two approaches that I use; I run a HERMS set up with a 20 gallon Infussion Mash Tun, using an external pump. The Vorlauf assembly is completely unnecessary as I see it, but it could be used, if you want to pump through it until the wort clears; as to the sparge arm, it is designed to just have water flow through it - used in the case of a fly sparge (again, I find it unnecessary).
YMMV, however. Find what works best for you and your system - Cheers!