FLAC compression levels are (only) a trade of between encoding time and file size. The decoding time is pretty much independent of compression rate. In the following I will refer to the compression levels 0, ..., 8 as FLAC-0, ..., FLAC-8.
In short: I recommend FLAC-4!
The Easy Solutions
If I don't care about encoding time and since space is ...
I would suggest naming them after the object that is the sound source for the recording. In the metadata you can then get descriptive and just add anything that would help you find them later into the keywords but as the main name I'd stick with source and other relevant details (e.g. induction_harddrive_writing_... or shorter ind_hd_writing ...).
What André said.
Then try describing what you HEAR. Buzz, hiss, whirr, growl, whine. You're basically putting keywords into the filename - good practice in my opinion.
If I was a sound editor/designer looking for buzzy, whiny electronic sounds, I would search my database for some of those adjectives first, unless i knew I had just the right recording of a ...