Regarding stretching: eggs are not uniform, and 150% is a general guideline, not a hard and fast rule. However, you may have your pen motor a little lower than it should be. The tapering at the tips may also increase the impression of it being squished. You could try raising your pen motor a bit and possibly stretching it by a few more percent.
Regarding printing off the edge of the page: the EggBot does not know there is an edge of the page, and you can use that to your advantage to make designs mesh well at the edges or to have continuous lines going around the egg multiple times.
The current version of the Inkscape extension is v. 2.4.0 dated 12/15/2015. There hasn’t ever been a “Check Motor Voltage” option.
