1. Not likely since it would mean either giving too much benefit to gladiators once PvP is implemented since they could just stun between normal attacks. Although the stun cannot be maintained indefinitely, it allow them to stun repeatedly over a short period of time and entirely disrupt any classes which have a casting time (TP costs don't mean anything for short fights). Even if so, they would likely end up balancing the skill around a 30 second cooldown instead... Which would render that whole strategy meaningless along with your intents here. If it's boring, find people who can run the instance without stunlocking the boss, or have people who alternate between stuns.

2. Likely related to the system they're using to host the instances or link characters across servers. Probably a technical impossibility.

3. Already on their list.

4. Would probably require a drastic change to how the duty finder is implemented and not worth the effort considering how few singular battles you usually enter into outside those story quests where you cannot proceed until doing those instances.

5. Been suggested several times, no official response.

6. While the notion behind a sort of auto-join system for the larger fates may sound like a good idea, such things only contribute to the lazyness of players and anti-social behavior. Have already seen a system similar to this in place on TERA. The result is that you have 1 or 2 people actually doing any fighting in the party while everyone else sits on the sidelines soaking up the exp and getting full credit. We already have this problem with instanced battles.

7. Been suggested several times, no official response.