Can I mana bolt a manifesting guy? What about astrally punching him with astral combat (without perceiving). The book says it's a psychic connection only, so I feel I can't but want to make sure.
No, and no.
When a Mage tries to manifest, they are just projecting a mental image of themselves across from the Astral. There is absolutely no substance to their form. It's like ghost Obi-Wan. Your Manabolt doesn't have anything to strike, nor do your fists, b/c you aren't Dual Natured at the time. If you were Dual Natured, you could do either of those things b/c at that point you would exist on the Astral as well. Your Manabolt and fists would strike their Astral Form directly. Note that if you cast a Manaball while Dual Natured, you need to decide whether you're casting it in the real world or the Astral. When it explodes into the AOE damage, it will only hurt one side or the other. You can't cast a Manaball and have it hurt both mundane people and Astral Mages at the same time.
PS Marcus Gideon: still away from DTF or ebooks for your quote. But I can tell you its in the artificing section of the CRB if you get closer to a book before me. (FWIW: was mostly useless. An attack on a foci from the astral deactivated the foci. Nothing more. No damage to the holder of the foci. And yes, he could activate it again next turn.)
Core pg 307, Disenchanting
The Disenchanting skill allows the magician to temporarily disrupt or even unweave astral constructs.
To deactivate an active focus, make an Opposed Disenchanting + Magic [Astral] v. target’s Force + owner’s Magic Test. You can do this from the physical or astral plane, though you must have line of sight to the focus. If you get more successes on the test, the focus deactivates.
With the Disenchanting skill, a focus can be effectively recycled, as a portion of the freed mana can recharge spent reagents. To break a focus down into reagents and totally destroy it, a magician must have touch contact with it. Breaking down a focus requires an Opposed Disenchanting + Magic [Astral] v. target’s Force (+ owner’s Magic if bonded and if the focus isn’t yours) Test.
This isn't a magical attack with a Manabolt spell. This is a particular application of the Disenchanting skill. You can either attempt to deactivate a Focus, either from the real world or from the Astral by targeting the Astral Form of the Focus. Or you can attempt to completely destroy the Focus, rendering it inert and extracting Reagents from it. But that can only be done in the real world, with the item in hand, and requires (Force) hours to perform.
And if you deactivate someone's Astral Form Weapon Focus, they can't just turn it back on. They have to return to their body first.