Finder doesn't show newly created files anymore unless restarted
From the output of your df -ki command, two numbers are telling you are beyond the red frontier of safe disk use.

Look at the line terminating with / which is your main visible and used disk partition. When the columns Capacity and %iused display numbers above 90%, then any search for a new free space or free inode is a real nightmare.
To tell you the truth the internal algorithm used by the MacOS X file system switched mode and is already in fight for breath.


When these two numbers are below 50% you are in the green area, nothing to schedule, just work.
When they are between 50% and 90% you are in the red one, you should schedule your next disk or computer buy.
Between 90% and 100% you are in the black area. You are fighting against a system in survival mode. Your risk of crash is pretty high. You can't anymore trust the journaling function.
At 100% you are not anywhere.


What to do

Estimate correctly your disk need for the next three years and buy a new disk. Once installed a new disk should let you with at least these two numbers below 50%.

Or, if this is feasable, change your disk space use to suit reality:


identify and clean garbage,
make external archives.