Anyone able to clarify how these would work?
The rules seem very vague in regards to both the construct limb and the grappling hook.
1. Is there a specific object, ledge or placement on where you can attach the hook too, or detach it?
2. Can a construct brawler climb it one handed, since his other hand is now a grappling hook with rope. Or can we use the standard action to reload to reel in the line and zip around?
3. Could you attach the grappling hook and rappel down a cliffside/building up to the 40ft?
I'll answer as best as i can for the RAW of it;
1: since the grapnel arm calls out specifically the grappling hook for how it mostly works, it can reasonably latch on to anything you could hook your hands on (much like actual grapple hooks), hitting non combat targets for this is AC:5, range incriment 10, range cap 40 (cause of the chain). For hitting a combat target its mostly the same except you target touch instead of 5. (So no worries about getting stuck, this aint a hookshot)
2: the reload is for the hook itself not the chain, so no spidermaning with it sadly. And theres nothing to say you don't have two hands, since the grapnel is part OF the prosthetic, it doesn't replace anything (look at the picture in the book for example).
3: yes you can, since the only differences between the grapnel and a normal grapple hook are; max 40ft, the special touch attack, it's attached to you, and it's fired instead of thrown.