Maximum unit attack speed and similar.

What is the minimum for Attack Cooldown Time ?
Does it depend on unit model? If it does how do I find it out?
Does attack speed depends on animation backswing point or animation damage point?
Does it depend on some other object editor fields?

In Gameplay Constants : Attack Speed Bonus per Agility Point,
does that directly substract from cooldown time or there is some other formula?

If unit has 2 sec attack cooldown and gets item that gives 30% increased attack speed, what will be the new cooldown?

From what I remember, so some of this may be wrong:
Without attack speed bonuses: 0.1 seconds
Attack speed bonuses may add up to +400% attack speed from the base cooldown, although there seems to be a limit of 0.0220

no

Animation damage point is when the attack occurs.

If (this+0.02 seconds) > cooldown, then (this+0.02 seconds) is the damage interval, else cooldown is the damage interval. (No idea where 0.02 comes from, but it was the same for multiple units).

It changes for attack speed bonuses the same way cooldown does, although the +factor seems to be slightly different.
Tested it a bit: It seems the (this+0.02 seconds) scales correctly with attack speed bonuses, but then another factor is added. At high speed bonuses this factor is +0.01, for lower bonuses it varies...

That is the % bonus per agility point.

Base cooldown*(100/(100+%bonus))
about 1.54 for 30% increase on 2 seconds

Are you saying that damage interval cannot be less than Animation Damage Point?

That it can't be less than Animation Damage Point+0.02 seconds when no speed bonuses are applied, yes.

Is there a way to increase the speed of unit attack animation?
(model animation not the damage point field)

The animations for actual attacks, spells, walk etc. aren't affected by SetUnitTimeScale are they.. damn.

They can be changed with attack speed altering abilities; so if say you want a slow attack, you could set the actual cooldown to normal, and then add a -50% attack speed bonus. It's quite a lame method, but it works.

The reason I ask all this is because some heroes see to have slow attack even with 400 AGI points due to model attack animation limits...

If you want more than this you need to replace with a new unit of lower base cooldown.