Getting these things right before you submit prevents rejections, stream count resets, and the kind of metadata errors that cost real money to fix after the fact.
Accepted formats: WAV (recommended), FLAC, AIFF. MP3 is accepted by most distributors but lossless formats are strongly preferred.
Minimum dimensions: 3000×3000 pixels (square).
Credits determine who gets paid when streaming royalties are distributed. Getting them wrong costs money and can damage working relationships.
Common split conventions (there are no rules, only norms): a sole writer/producer typically takes 100%, co-written tracks often split 50/50, a producer and a writer might split 50/50 or agree by contribution.