Hello, all.

Is there a good tag editor for APE?
Does APE tag support unicode?
How to write APE tag and read APE tag in foobar 2k?

Sincerely..

* Foobar2000 supports APE tags for mp3 files, so I assume that it works well to edit APE tags on APE files.
* I assume that APE supports Unicode, but I'm not sure - I've never run into a character that it couldn't save
* Within Foobar2000, you can edit the tags field-by-field for both individual files or for a group of files (by either higlighting whatever files you want to edit and right-clicking and choosing "properties".
Also, you can use the masstagger function by rightclicking and selecting
Masstagger --> Edit Tags
Play around with the options when Masstagger comes up - it's not too hard to figure out. You can set up profiles for automatically tagging files based on the filename - for example, I've set up a profile called "A--T, no underscores", composed of these three commands:
Guess values from filename - %artist%--%title%
Format ARTIST using $replace(%artist%,'_',' ')
Format TITLE using $replace(%title%,'_',' ')

(The format commands are necessary because I name my files with underscores instead of spaces, but want the tag information to have spaces instead of underscores).