The system is not changing the current make your own class system. the specializations are simply two categories that give minor bonuses and allow everyone else to see what type of character you are playing. Gladiators can play both DD or tank right now, but there is no way for other people to tell what their specialty is when looking at that character. Basically you play the game as you currently play, choose your specializations, and get some minor bonuses while letting everyone else know what you are playing. the title system is also simply a way to bring back old job names, which some people have asked for. titles are something that must be quested for and unlocked.
Example: a character is playing a gladiator, and prefers to play a tank. He sets up abilities to support that role and then chooses specializations that support that role. For a paladin-like tank, the player would set up cure abilities, provoke abilities, shield abilities, and then have specialties like defense and support. If the player then decides that he really likes playing this type of character, he can quest for the paladin title, which can be set while (defense/support) and gives additional minor bonuses befitting the title.
The player may later decide that he wants to play a damage dealer, in which case he sets up new abilities and chooses new specializations.
As for the universal cool-down, there are a number of cool-down timer in the game currently.
1. Recast timer - the amount of time before an ability can be used
2. stamina bar - an overall cool-down timer
3. ability use time - the amount of time the ability takes to use.
of the three cool-downs, one is per ability, and the other 2 are universal.
recast time is per ability, and the ability to use that ability is not depended on the recast timers of other abilities (except shared cool-downs)
The stamina bar is a universal cool-down, as using one ability affects the ability to use another by way of the stamina bar.
The ability use time also acts as a universal cool-down since other abilities cannot be used until the current ability is finished. proving it is a universal cool-down is quite simple. wait till you have full stamina, then cast cure; as soon as your stamina bar is full (which is before cure finishes casting) hit another ability, if the ability does not go off then there was a universal cool-down.
even with the stamina bar removed, there is still a universal cool-down on every ability, including basic attacks. This is the action use time. some actions may have a recast time of 0:00, but that does not mean they could be spammed.