5 & 6. Worf and Martok
It actually makes pretty good sense to bring back both Worf and Martok. We'll take Martok first he's the Klingon Chancellor last time I checked, so presumably he would still hold that position (although he doesn't in Star Trek: Online). J.G. Hertzler is also playing a character under a bucketload of make up for Star Trek: Renegades, so he might be willing to resume the role of Martok especially as he also still does so at conventions. As for Michael Dorn as Worf... well he wants his own Captain Worf television show. So he wants to come back to the role. As for what role Worf himself would take, well there are a variety of possibilities. Captain is only one of them, as is Ambassador, Admiral, Commodore not to mention where Star Trek: Online places the character. Essentially if you are going to feature the inner workings of the Klingon government in a series set within about 20 years of post-Voyager then both of these characters should be involved.