Glad you're enjoying it! 0.4 will be out on Friday, including some new characters and a Story Hints function to give you a better idea how to proceed with their plotlines. There will also be a tab for them in the People dialog so you can see all the ones you've met in one place.
Summit Market mostly suffers from being the first entire event set I ever wrote for this project... and yeah, it's a bit lacking! But there's a contributor working on expanding that job.
NPC customization is something I'll look into. Changing their gender should probably mostly not cause problems... changing their name has some pitfalls, since it's also their data key and generation seed, but those things can be overcome.