I haven't given a ton of thought to the rarities, but that's a good idea because the stars are kind of unintuitive.
I'll definitely be adding a feature to keep track of which items you've collected, with an appropriate reward for completing the collection.
The next update should be the last one for free demos, I'm probably going to switch over to Steam early access in January, but I'll be sure to pass a key your way when that happens.
I'm also going to take some time to add a save exporter in this month's update. I can't replicate that crafting bug you're seeing, so hopefully that will help me grab different people's games and sort things out. It would also let people transfer their games from the web version to the desktop version.