We are going to finish V0.3 first for the old Mount&Blade. I am also considering to make V0.3 a WIP release because it would take a very much amount of time to make everything perfect. And some bugtesting wouldn't be wrong at this point.
I hope to include more special stuff such as quests and such in Warband. I doubt new quests will be in V0.3, mostly features and new models & troops and such. I hope to post some progress soon, to inform you how far we already are.