1. You're fine.
2. By letting him do what makes him heroic: Questing
3. By taking away power and or making even more powerfull villains that remain hidden and send menacing henchmen towards the two (menace while they quest/reasons for quests)
4. Training montage! => (A couple months pass, in this time, please state how your characters have spent their time, but talk it over with the GM first.)
5. Ehh.. well.. The flow of time is not something that always mixes and matches everything together nicely... O.o But then again, a second and or third problem/distraction can give other plotpoints time to develop.
6. Weak king. Compared to what? Weak financially? Weak emotionally? Does he not have a list of "close friends that owe him a favor or 42" or is he physically weakened? O.o
7. They don't know that actually. I'm certain it won't take another bodyscorching to convince ravadon the dragon did something bad to him. A prophecy, a doomsayer, a magazine(with the dragons dirty laundry in it) in the hands of the right person...
8. Planning. The void does what to cause all these events to happen? Does it burn down powerstructures? Does it hold the dragon captive? Does it seek to summon an ancient evil that would take over the void and doom the world? O.o 

[i]*Raises helpful hand*[/i]