Shell Script for Bulk Filename Editing

I need a shell script to edit filenames in a directory.

Requirements:
- Process all files in a directory.
- Remove specific characters:
- Spaces
- Underscores
- Numbers
- All leading characters before the name of a group/band from mp3 files.

Ideal Skills and Experience:
- Proficiency in shell scripting
- Experience with file manipulation and pattern matching in Linux/Unix systems
- Familiarity with mp3 file formats and naming conventions

Please provide a script that is efficient and well-commented for future modifications.