Yes, as Doppel said you should set the sampling to point. That will take care of the blurriness.
As for he rest, I've run into this exact problem with my game. I asked Ashley about the scrolling issue and he said that due to the way Construct scales things up it would be too hard to change, so he offered up a solution:
Solution 1. You can check "Unbounded scrolling" in the layer properties.
Problems with this solution:
- This will make the outside of your level visible, so you have to fill it with graphics.
- It also means that your player will be in the exact center of your screen at all times, even when at the edge of your level, because Construct is scrolling outside of your level.
Solution 2: Make some extra space around the edge of your level to compensate for your zoomed screen size. Like this: http://i25.tinypic.com/35hpgfr.jpg Just make sure that Unbounded Scrolling is un-checked. This will make your screen scroll normally. If you want to see it in action, here's a demo of my game: http://willhostforfood.com/access.php?fileid=17966
Problems with this solution:
- It makes your level bigger than it needs to be.
- You will need to rearrange all your tiles.
If you have any questions, feel free to ask.