I think this falls into another category of 4e really bottlenecking ideas. If you want to fight with two weapons, play a ranger. Otherwise keep your mouth shut. Don't use your imagination to bridge ideas between classes. Put that javelin down, Mr. Fighter. You use a shield.
As far as I'm concerned, the bursts detail themselves enough for satisfaction (as all directions includes up and down).
As for blasts, you could apply the same reasoning thus, so a blast 3 is a 3x3x3 cube. However, this means you have to apply this to creature size (so large creatures are...
Maybe
I think the fact that the Elven Accuracy ability specifically states "use the second roll even if it is lower" precludes any further rerolling.
So, a 30th level Demigod could certainly reroll every attack roll a single time, if he felt that was worth having to blow all his other...