[DaveBlake]

Also, I would like to retain a year for each song and be able to search the library and see every song from say...1982. What is the best way to tag for this? Is it best to just do a filename search and put it in the file...ex. Soft Cell - Tainted Love (1982) ? Or...should I make it Artist: Soft Cell, Title: Tainted Love, Year: 1982?

Use the year tag - YEAR in FLAC files or ID3v1, and TYER or TDRC or TDRL in ID3v2.

Do I also need to put Albumartist= Soft Cell for singles (my current practice)?

No need to do this, but no harm either. When album title is blank Kodi takes the file as a "single" and uses the song artist as it needs to.

And what is "best practice" for compilations/ soundtracks? What about single tracks that are not on any album?

Took this last. The other big question is what to do with music that has more than one artist? All classical music is like that - composer, conductor, orchestra, soloist - although you would probably put albums under a composer folder, But you get collaborations in other genres e.g. B.B.King & Eric Clapton "Driving With The King".

Also what to do when you have different artists with the same name e.g. John Williams conductor and composer of film music verses John Williams classical guitar player?

In truth the folder structure is not too important to Kodi as long as you are not using local artwork or NFO files which currently depends on a artist>album hierarchy and handles compilations, collaborations, non-unique artist names and singles badly. Something on my long list to improve.

So that all said for now DarkHelmet's suggestions for compilations and soundtracks are good for ensuring that Kodi finds any local artist artwork etc. Personally I would put all the singles under the artist folder, but it depends how many you have and how you like to order your data. I would also put collaborations under a separate folder or folders too, knowing that Kodi can't cope with artwork or NFO for them.

Also after using Kodi for a while I discovered the usefulness of having separate/multiple music sources. I started with my top level folder as the only source, as the initial post describes, but now organise my files so that my classical music, soundtracks, and compilations are all separate sources to the main (pop) music.