As for your other questions:
The worst case scenario is that people won’t use the plugin if it doesn’t meet their expectations. Since it is a plugin and not part of Discourse core, there is very little downside to it. Having said that, in the spirit of open source, if you guys make a great effort and put your results out there, someone else can come along and champion it / move it forward. I wouldn’t worry about this and just do your best!
If you finish early and are still interested in the project, there is a lot more we could add to it! I scoped out what I think is a simple an realistic version to finish, but we could really add a bunch of more advanced functionality to it. I don’t think it would be hard to find new and awesome features to add to it.