Okay, so Dual Natured and Astrally Perceiving (aka "AR of the Astral World") characters are able to attack physical beings normally with physical attacks. Astrally Projecting characters are unable to affect physical beings (hope I'm right so far).

All three of them can fight wholey astral entities by rolling Astral Combat + Willpower. What does their target roll in the opposed test? Normally it's Reaction+Dodge for melee, and the Astral equivalent of Reaction is Intuition. So do they roll Intuition+Dodge or just Intuition? Can they go Full Defense?

Okay, so the damage is specified on that table for each different type of astral entity, and I'd assume every net hit on the previous test adds to this. Damage resistance rolls are normally Body + Armor. Body would become Willpower, correct? I doubt it, but is Armor added to the roll? What about magical armor spells? Does armor penetration from weapon foci apply? If the modified DV is greater than the modified armor value, can the attack only deal stun (as opposed to giving the attacker a choice between stun or physical)?

After the damage resistance check, is there a chance of astral knockdown? (is it even possible to be "prone" in the astral plane?)

Thanks for the replies. One big question that's been bothering me all this time...

Why would anyone want to be a hermetic mage, which relies partly on Logic for resisting drain? Shamans (Charisma) and theoretical Intuition-based spellcasters can double-up with related astral combat abilities (Cha=DV, Int=defense) or related skills (cha=social situations, int=perception/initiative), but the main use of Logic seems to be for technical skills, which magic users tend not to mess with anyway. There's First Aid and Medicine, as well as extra Knowledge skills, but that's really about it. Am I missing something?

EDIT:
Though, Agility is replaced by Logic on the Astral Plane. Hmm, let's see... By nixing all the combat skills in Agility, we are left with:
Escape Artist: Don't think it's possible to get "tied up" out here
Forgery: Astral signature forgery? haha, I don't know.
Gymnastics: If we can fly, then worthless.
Infiltration: Could be very useful (I haven't read the whole Astral section, so I don't know what they say about being stealthy in astral space)
Locksmith: Useless.
Palming: No idea how that would work.

EDIT #2:
DOH! Here's a nice one to think about:
"The number of foci you can have active at one time is equal to your Logic."
I take it back.

- knowledge skills, in SR3 at least, included spell and enchanting design. quite likely they will in SR4 as well, if you ask me.
- computer skills, electronic skills, and biotech skills can be useful to anyone. magician or not. for example, you can cast Heal, which drains you, or you can use first aid, which doesn't. you can burn through the maglock door with acid, which drains you (and sets off an alarm, i am sure) or you can bypass it with electronics. it's also not at all a bad idea to have electronic warfare skills available, in case it comes up. especially if you make use of drones. (remember, you're a magician, which means you don't spend all your cash on cyberware, so you gotta find something to spend on)