Re: Problems with even Strokes
To me this is just using one shape and then going to Object and then down to Path and then going out and selecting "Offset Path". If you have set your Preferences to pix then the offset will also be in pix. I would have used the Pathfinder Tool to join 2 modified rounded rectangles together to get your shape then you will need to do this again to your Offset Path shape as it will come up again as 2 modified rectangles. That's the way I would have done it anyway to get your shape and holding shift and the hitting "add shape" in the pathfinder.
Design is thinking made visual.