Looks about right. Sad that Oberyn will be a one-season wonder though. Probably only see him in 3 or 4 episodes and his death won't have nearly the impact as if he were around this season.
That is going to be an increasing problem as the series continues. Unless you start introducing these characters and giving them proper development early on, the deaths are just going to start seeming routine. "Oh, look at the guest star this season who will obviously die in episode 9"
It's one of the disadvantages of the show, not being able to go in depth like the books, but I like the Season 4 will be having its own flavor with the new characters from Dorne. The Oberyn vs the Mountain fight should be epic.