Thanks for a feedback. I was just gonna respond you can customize controls, but just checked and that particular one is not customizable! I think I did not added it to the list because I'm gonna remove either G or J. Since J is more advanced I would basically hook the functionality from J under the G and G key is already customizable.
Regarding the font in the hot bar - I will enhance it with the next release (this weekend?). Actually just before the full launch (Q3 this year) I'm planning to change Options screen completely - there will be a lot of things customizable as each person has bit different needs. But this is a task I'm leaving as last one as core mechanics must be done first.
Keep playing!