Thanks for the input. I don't plan on working as a 3D Modeller but still I figure from your answers that I should neglect sculpting (tools) for the time being. I will try to find some learning material for Maya then, since it's an industrie standard and thus should work flawlessly with Unity3D and I will keep Blender as a fallback option.
Nobody mentioned tools like Cinema 4D, Cheetah3d, Modo or Lightwave - so I guess those are outdated.
Well Jimmy already got you covered, but your source code also seems to be messed up a bit. You have the summary of your loadcontent method inside your initialize method and the Texture2d should be a class member I think. I'm not sure what you want to with MaxX in the update but ok.
So you don't really need to change your draw method, only the update(). You need to adjust the spriteposition according to button presses. Add a new class member
and in the update() check for key presses and update the position, for example:
currentKeyboardState = Keyboard.GetState();
spritePosition.X += 1f;
You have to test different values here. And to find out how big your window is, well you already got it I think: graphics.GraphicsDevice.Viewport.Width
So you should wrap another if statement and check if the spriteposition is within the viewport, and if not you do not increase the position any further.
I hope that helps a bit, but the best thing is to get some book on XNA or use the online educational resources over at the Microsoft page. There are a few XNA books freely available on books.google.com I think.
Well I'm a Newbie myself but you have to go with a Tile Map and I don't really know why it should not be able to draw big maps. I mean your drawing code should always only draw the visible portion of the map.
You can check out tiled (mapeditor.org)- so you already have a mapeditor and you got the assets. And you can still have transitions between the maps - even Diablo did have those.