"Greg Esres" wrote in message

1) Could I have possibly damaged anything by running the unit with
almost no air intake for 30 minutes?

No, it would take many hours.


2) I anticipated leaving the unit with air in the tank all the time,
but the instuctions hint that the air should be drained after every
use. What's common practice here?

You can leave it in. If you have no leaks, it will hold pressure forever.
Most system have at least tiny leaks and the compressor will cycle if left
on. Depending on your use, water will accumulate in the tank at times and
it should be drained occasionally. I drain mine abut once a year, but some
with heavy use need draining a coupleof times a day. .