1. I believe they are putting in chests/gear/tomes every time you use the DF, or at least the dungeons ala Rift and WoW. This was coming in 2.1 I I think.

2. Yes, more dungeons, the better! I'm sure the extreme modes will give the Myth tomes, so you will get your wish, kind of. That is also in 2.1.

3. FF does it differently than other MMO's. Every Job will be the same. As every job is like a specialization unlike in other games. Like in WoW, you can be a Pally Tank, DPS or Healer. In this game they are just broken up into jobs. And more will be added. So the idea as you described will not happen in this game. They will just add Jobs.

4. Global cooldown will not be adjusted. This was obviously a very careful design feature of the combat system. I believe it's so the console people have a chance at being viable as they have to use a combination of commands to get to their skills. I wouldn't look for this to be changed any time soon.