Yeah, I'll work on the balance.
Regarding the drills, there is a bug when they just disappear (it's going to be fixed). Other than that, you just need to manually start the drills and wait for them to mine some ores. You can also melt your items, if you really don't want to wait.
Other flowers produce more oxygen (green one produces the most), so planting them should help. I'll add a proper explanation for that and lower the requirements (at least for the normal difficulty)
Thanks for playing and sharing with your feedback!