Skill, Mechanics and Definitions.

Defenses
There are 3 types of defenses in SWG. Primary, Secondary and State defenses.

Primary Defenses
Melee and Ranged Defenses are primary defenses. These defenses work regardless of what weapon a character is wielding. These defenses are rolled against accuracy to see if an attack is successful. Currently these defenses are capped at 125. Only Chef food, Squad Leader and City bonuses can take these over the 125 cap.

Secondary Defenses
Dodge, Counter Attack and Block are secondary defenses. These defenses are weapon dependant. Pistols and 1-handed melee weapons use dodge. Carbines and 2-handed melee weapons use counter attack. Rifles and Polearms use Block. These defenses come into play if and only if the proper weapon is equipped and a hit is successful against the primary defenses. These defenses do not block scatter hits, unarmed combos, bleeds or DOTs. Currently these defenses are capped at 125. Only Center of Being and Chef food bonuses can take these over the 125 cap.

Center of Being is a brawler skill that boosts secondary defenses. The bonus is directly added to the secondary defense. CoB is also weapon dependant, meaning that if CoB is active for 2-handed Melee, it must be reapplied if you switch to a 1-handed Melee weapon.

Defense Accuity is a Teras Kasi skill. Defense Accuity has a random chance to either Block, Dodge or Counterattack. While many complain that this skill is not working, my own testing shows that it does indeed work, is affected by CoB, but has a lower chance of working due to comparably lower value to the other secondary defenses.
From my understanding. Accuity is like a second chance def if your melee and ranged def fails. How ever while intimidated your def accuity can still function (un like your secondary skills such as dodge etc) since it is triggered off primary defences not secondary defences.

State Defenses
Defense vs. xxx are state defenses. State defenses are a roll against accuracy to see if a state is applied. Each state skill then has an inherent chance to succeed upon a successful roll. Currently all these defenses stack across professions, but have a 95% cap. In other words, no matter how high your state defenses there is always a 5% chance that a succesful 'state hit' will be applied. When a successful 'state hit' is applied, there is then a percent chance based on the skill for it to work.

Defense vs. Knockdown - This defense is currently working. 70+ in this skill is recommended for a noticeable difference. Thakitillo Chef food provides 80% defense for 10 minutes (Highly recommended for those lacking this defense.)

Defense vs. Posture Down - This defense is currently working. It is more difficult to achieve high defense in this skill. No Chef food exsists.

Defense vs. Dizzy - This defense is currently working. Dizzy is what makes Knock Down and Posture Down so dangerous. Any attempt to change posture, even if you are currently in that posture (i.e. hitting stand while standing) results in a chance for a person to fall down.

Defense vs. Blind - This defense is currently working. Blind significantly lowers an attackers accuracy. It is estimated at applying -50 accuracy.

Defense vs. Stun - This defense is currently working. Stun halves the attacker's damage and also lowers primary defenses by -50 defense.

Defense vs. Intimidate - This defense is currently NOT working. Even at 90+ defense a novice brawler with no bonuses will land intimidate 50% of the time. Intimidate halves the attacker's damage, lowers state defenses and negates all secondary defenses.

My experience has shown that certain state defenses matter more than others and that certain states are harder to defend against than others. It is also important to note that because accuracy plays a role in determining the success of a defense it is much better to have 100 in one defense than 50 in two defenses. A player with 75 melee, ranged and secondary defenses will be hit significantly more than a person with 0 melee and ranged defense but 125 secondary defense. A person with 50 def vs. knockdown and 50 def vs. dizzy will be much easier to apply kd/dizzy to than a person with 0 defense vs. knockdown and 100 defense vs. dizzy. Min/Maxing of skills is just that. Maxing what skills you choose to and minimizing wasted skill points.

Accuracy
Accuracy is very simple. The higher your accuracy the better chance you have to hit something and applying a desired effect/state. Accuracy should be maxed if possible, especially against targets with high defense. It is important to understand that your posture, the target's posture, the target's defenses, intimidate on the target, stun on the target, blind state on the attacker, aim, range modifiers on the weapon and rate of movement of both you and the target severly affect accuracy. Use all these to your advantage whether you are the attacker or the defender.
(Example.... Stationary target is harder to hit than one that is moving and fighting back)

Speed
Speed works on an exponential scale in SWG. It is a continous curve that is near constant at lower speed and then rises sharply as speed approaches 100. Speed is capped at 1 second in SWG. Any attacks that appear faster are due to lag. Due to SWG's speed formula any weapon can be used at 1 attack per second at 100 speed. Due to inherent weapon speed and special attack delay modifiers, all weapon have a different cap which is below 100. What is most important to note is that as you approach 100 speed, each bit of weapon speed significantly increases attack speed until you hit the one second cap (i.e. the difference between 75 speed and 85 speed is significantly lower than the difference between 85 speed and 95 speed when using a 5.4 speed Power Hammer with Head Hit 3 in 2-handed melee).

Damage
Random HAM vs. Targeted HAM. Random HAM attacks are typically higher damaging attacks. Targeted HAM attacks are typically lower damage but only hit one pool. Your target, your special attack and the group you are attacking with all determine what is the best type of damage to deal when comparing Random HAM vs. Target HAM attacks.

Mind Damage vs. Health/Action Damage. Mind Damage is unhealable in SWG. The Mind stats are also the most difficult to buff. In PvE, the difference between attacking a targets mind vs attacking health or action is not real significant. The only exception is against certain NPCs that can heal themselves. In PvP, mind damage is king. Health and Action stats are often times 2-3x higher than mind stats. Given the reduced pool size, reduced regeneration and unhealable quality of mind, mind attacks are far more effective than health/action attacks in PvP.

Mitigation
There are two types of mitigation in SWG, melee and ranged. Mitigation reduces the difference between max and min damage on an attackers weapon. Mitigation 1 is 20% reduction, Mitigation 2 is 40% reduction and Mitigation 3 is 60% reduction. Example: An attacker is using a weapon with 50-150 damage against a Mitigation 3 target. The attackers damage spread is 100. Mitigation reduces this by 60% making it a 40 damage spread. Effectively, the attacker's weapon now is a 50-90 damage weapon.

Mitigation cannot be stacked. Mitigation is always in effect regardless of the weapon you are using. Your highest level of mitigation will always be used. A person with Ranged Mitigation 1 from Carbine, Ranged Mitigation 3 from Rifle, Melee Mitigation 2 from TK and Melee Mitigation 3 from Fencer will always have Ranged Mitigation 3 and Melee Mitigation 3.