Can it split longer mp3 files automatically?

Can Picard split automatically mp3 files, depending on silence - or do I need extra tools as mp3split / mp3splt before I can use Brainz? Or is there maybe a plugin for this purpose?

Quick answer - no. Picard is a tagger, not an editor. You’ll need to slice the files up yourself. Do you have a cue file with it to get the track details?