Great work! Glad to see your enjoying the software.
Just a quick note on the size, you can have a 32px generation grid and set the 'Output Scale' under 'Generation Settings' panel to '2x'. This would give you a pixel perfect 64px sprite. If your using batch output make sure you change 'Scale' to "Scaled' which will use whatever 'Output Scale' you have set.
Cheers, TomC