There is a great article on irrimi from Amdur Sensei in the forums right now that I think cuts to the heart of this question. Kuzushi is achieved through irrimi. That is to say the I must always enter to connect to my parter's balance structure before
I can perform waza. Kuriowa Sensei called this action "kihon" because it referred to the basic interaction of every aikido technique, "aiki". So "kihon waza" referred to the spontaneous technique resulting after a stated of aiki was established. Specify the technique and you have kata no kihon waza. I really liked the approach Kuriowa Sensei had in this regard because I think we often put the cart before the horse when we try to do technique before
we are connected to our partner's balance. If we lose aiki, then we need to establish it again... with another entering move.
While not aikido, it is often easy to spot the entering movement in a good judo match - you can almost see tori's balance go out the window. If somehow tori moves his center and restructures his balance you see another entering movement (and so on). Sometimes its easier to see this transition in judo because the moves are larger and less subtle than in aikido. Eventually, I think the good judo players are simply doing aiki and you're back to having difficulty seeing what is going on.
Timing and distance are components of the entering move. However, both are based upon the attack, not the attacker. I tend to agree with Kevin on this... I would be careful to distinguish between the timing of my partner's action and the timing of the attack. Anyone who has ever heard a 5th grade musical can attest to the fact there is music on a sheet and there is music that is being played, they are not necessarily the same. I should be able to make the same technique work whether I am 3 feet away or 3 inches away (sorry, I don't know the conversions for all your metric freaks