Wow, thanks for the detailed post!
1. This seems to be a visual bug since I only provided 30 hearts/gems. I've added 10 more in 0.93 to help with this. I might revisit again later to make the UI more flexible to allow any amount.
2. I found this bug when making Blood Moon! Also fixed in 0.93!
3. If you ever get this to occur again and have more information I would really appreciate it! I believe it might have to do with retrying after using potions, but I thought I had fixed that in the past...
4. That one is interesting.. I do have logic that prevents items from being shown if you have "Max" amount of them. Most passives are Max of 1 but there's nothing stopping it by floor. I'll look into it
5. Fixed in 0.93! Thanks for the report :)
As for your suggestions for QOL in the inventory -- all are valid. I'll spend some time giving the inventory some love in the near future.
And as for Business Card... I'll consider it... I do think it's the best item in the game even with that debuff. What about removing it, but making Humanoids +1 damage or -1xp? I just worry without a negative offset it becomes 1000% the best item in the game!
If you got any other balance/content ideas, let me know!
Thanks again for playing!!!!!