"I think they're called grants"
I don't believe so. I believe the grant is the small vessel that the lauter tun outlets flow into before moving on to the boil kettle. It's an intermediate vessel between the two. I actually use one. It's automated.
"There are multiple capture points and the idea is to separate the later tun from pump suction so you dont cause the bed to get stuck"
I've heard others say this or something similar. But I don't get it. Take a bucket of water and set it on a countertop. Put a second bucket on the floor. Now take 10 feet or so of tubing and start a syphon, moving fluid from the upper to the lower bucket. While its syphoning, do anything you want with the tubing as long as the top end stays in the bottom of the upper bucket and the bottom end stays in the bottom of the bottom bucket. You'll find that the shape you contort the tubing into makes no difference in the rate of flow in the syphon. You can make a 'gooseneck', or coil it round and round, it makes no difference. Same flow no matter what, given same endpoints. If you think about this it makes sense because whatever flow shape you create, the flow has to travel downward the exact same distance as the upward part of your creation. The two nullify each other and you're left with the same flow. In fact, you can create a 'gooseneck' with a flow shape that goes well above the top bucket (and back down, of course) with no change in flow rate.
So... I still don't get it.