Glad you're enjoying the games!
Well, the model used here is basically similar to that of AI War, rather than Tidalis -- there is a viewport, and if you use a larger resolution then the HUD is smaller and the viewport reveals more of the world. There will probably need to be some sort of zooming ability so that players with small resolutions or similar could adjust upwards, but that hasn't been fully thought through yet, honestly. At the moment the goal is to support 800x600 and up, and any combinations of widescreen, etc, will work.
In terms of the super widescreen like EyeFinity, if it works for AI War, it works here. But I think that will only work in windowed mode, based on how Unity handles things. We can't add support for anything of that nature that unity (the engine we use) doesn't support, unfortunately.
In terms of general scaling of things like the HUD, etc: as with Tidalis, our message is basically that you should use a smaller screen resolution if you want it scaled. No running at a massive resolution just for the heck of it, only use that if you want to see that much of the playing field at once. If it makes the text too tiny, then the characters and such are probably also too tiny (as with AI War). The GPU is much better at scaling the entire resolution than it is at scaling every element individually to achieve the same effect, and using smaller resolutions will lead to improved performance in general, as with most games (and AI War). The effect of that will likely be more pronounced with this game than with AI War.
That said, we're shooting for 60fps, but will support different framerates, and in most cases so far my desktop 8800GTS is running 1280x1024 and getting about 200fps at minimum, even with a ton of grass, etc, onscreen at once. That will drop some as more elements are added to the game, but probably it won't even get down to 60fps in most cases. Sometimes it's closer to 600fps at the moment. On my Mac laptop, 200fps is about the best I get, and it drops to 80 or even 50fps at times, depending on what is going on. That's at 1280x720.
I should also note that some of the interior areas will wind up being smaller than the viewport, depending on how big your screen is. If you step into a small shack, then you'll see just a tiny amount of the screen used to draw the inside of the shack, and then blackness around it for the rest. For all exterior areas, caves, and so on, that wouldn't be something that would come up, as those areas are pretty huge!